topics

! indicates an important subject

✗ are entries that I haven't looked at.

  ✗  access driver  In the external table infrastructure, the API that interprets the external data for the database. The access driver runs inside the database, which uses the driver to read the data in the external table.  

  ✗  access path  The means by which data is retrieved from a database. For example, a query using an index and a query using a full table scan use different access paths.  

  ✗  ACID properties  The basic properties of a database transaction that all Oracle Database transactions must obey. ACID is an acronym for atomicity, consistency, isolation, and durability.  

  ✗  active online redo log file  An online redo log file that may contain data that is required for instance recovery.  

  ✗  active session  A database session that is using CPU and is not waiting for an event in the idle wait class.  

  ✗  Active Session History (ASH)  A part of the database self-management framework that samples active database sessions each second, writing the data to memory and persistent storage.  

  ✗  active transaction  A transaction that has started but not yet committed or rolled back.  

  ✗  Adaptive query optimization  A set of capabilities that enables the adaptive optimizer to make run-time adjustments to execution plans and discover additional information that can lead to better optimizer statistics. Adaptive optimization is helpful when existing statistics are not sufficient to generate an optimal plan.

  !  ADDM  Automatic Database Diagnostic Monitor. An Oracle Database infrastructure that enables a database to diagnose its own performance and determine how identified problems could be resolved.  

  !  ADR  Automatic Diagnostic Repository. A file-based hierarchical data store for managing information, including network tracing and logging.

  !  ADR base  The ADR root directory. The ADR base can contain multiple ADR homes, where each ADR home is the root directory for all diagnostic data—traces, dumps, the alert log, and so on—for an instance of an Oracle product or component.  

  !  ADR home  The root directory for all diagnostic data—traces, dumps, the alert log, and so on—for an instance of an Oracle product or component. For example, in an Oracle RAC environment with shared storage and Oracle ASM, each database instance and each Oracle ASM instance has its own ADR home.  

  ✗  advanced index compression  An extension and enhancement of prefix compression for supported unique and non-unique indexes on heap-organized tables. Unlike prefix compression, which uses fixed duplicate key elimination for every block, advanced compression uses adaptive duplicate key elimination on a per-block basis.  

  ✗  advanced row compression  A type of table compression, intended for OLTP applications, that compresses data manipulated by any SQL operation.  See also basic table compression.  

  ✗  aggregate function  A function such as COUNT that operates on a group of rows to return a single row as a result.  

  ✓  alert log alert log  The alert log stores database messages (also error messages) in chronological order.  

  ✗  analytic function  A function that operates on a group of rows to return multiple rows as a result.  

  ✗  analytic query  A "what if" query that answers a business question. Typically, analytic queries involve joins and aggregation, and require scanning a very large amount of input data to produce a relatively small amount of output.  

  ✗  analytic view  A type of view that encapsulates aggregations, calculations, and joins of fact data. Analytic views organize data using a dimensional model. They allow you to easily add aggregations and calculations to data sets and to present data in views that can be queried with relatively simple SQL.  

  ✗  antijoin  A join that returns rows from the left side of the predicate for which there are no corresponding rows on the right side of the predicate.  

  ✗  application  Within an application root, an application is a named, versioned set of data and metadata created by a common user. An application might include an application common user, an application common object, or some multiple and combination of the preceding.  application architecture The computing environment in which a database application connects to an Oracle database. The two most common database architectures are client/server and multitier.  

  !  application container  A named set of application PDBs plugged in to an application root. An application container may contain an application seed.  application context An attribute name-value pair in a specified namespace. Applications set various contexts before executing actions on the database.  

  !  Application Continuity  A feature that enables the replay, in a nondisruptive and rapid manner, of a request against the database after a recoverable error that makes the database session unavailable.  

  ✗  application domain index  A customized index specific to an application.  

  !  application PDB  A PDB that is plugged in to an application container.  application root The root container within an application container. Every application container has exactly one application root. An application root shares some characteristics with the CDB root, because it can contain common objects, and some characteristics with a PDB, because it is created with the CREATE PLUGGABLE DATABASE statement.  application server Software that provides an interface between the client and one or more database servers, and hosts the applications.  

  ✗  Oracle: archival backup 

  ✗  archive compression  Hybrid Columnar Compression specified with COLUMN STORE COMPRESS FOR ARCHIVE. This type uses higher compression ratios than COLUMN STORE COMPRESS FOR QUERY, and is useful for compressing data that will be stored for long periods of time.

  ✗  archived redo log file  A member of the online redo log that has been archived by Oracle Database. The archived redo log files can be applied to a database backup in media recovery.

  !  ARCHIVELOG mode  A mode of the database that enables the archiving of the online redo log.  

  ✗  archiver process (ARCn)  ARCn is a background process that archives online redo log files.  

  ✗  archiving  The operation of generating an archived redo log file

  ✗  ascending index  An index in which data is stored in ascending order. By default, character data is ordered by the binary values contained in each byte of the value, numeric data from smallest to largest number, and date from earliest to latest value.  

  ✗  attribute-clustered table  A heap-organized table that stores data in close proximity on disk based on user-specified clustering directives.  

  ✗  audit trail  A location that stores audit records.  

  !  Automatic Database Diagnostic Monitor (ADDM)  See ADDM.  

  !  Automatic Diagnostic Repository (ADR) 

  ✗  automatic memory management  The mode in which Oracle Database manages the SGA and instance PGA memory completely automatically.  

  ✗  automatic segment space management (ASSM)  A method of storage space management that uses bitmaps to manage segment space instead of free lists.  

  ✗  automatic undo management mode  A mode of the database in which it automatically manages undo space in a dedicated undo tablespace.  

  ✗  See also manual undo management mode.  

  ✗  Automatic Workload Repository (AWR)  See AWR.  

  ✗  autonomous transaction  A independent transaction that can be called from another transaction, called the main transaction.  

  !  AWR  Automatic Workload Repository (AWR). A built-in repository in every Oracle database. Oracle Database periodically makes a snapshot of its vital statistics and workload information and stores them in AWR.  

  !  AWR baseline  A collection of statistic rates usually taken over a period when the system is performing well at peak load 

  !  AWR snapshot  A set of performance statistics captured in AWR at a specific time.  

  ✗  B-tree index  An index organized like an upside-down tree. A B-tree index has two types of blocks: branch blocks for searching and leaf blocks that store values. The leaf blocks contain every indexed data value and a corresponding rowid used to locate the actual row. The "B" stands for "balanced" because all leaf blocks automatically stay at the same depth.  

  ✗  background process  A process that consolidates functions that would otherwise be handled by multiple Oracle programs running for each client process. The background processes asynchronously perform I/O and monitor other Oracle processes.  

  ✗  See also database instance; Oracle process.  

  !  backup  A copy of data. A backup can include crucial parts of the database such as data files, the server parameter file file, and control file.

  !  backup piece  The smallest unit of a backup set.  

  ✗  backup piece  The physical file format used to store an RMAN backup set. Each logical backup set contains one or more physical backup pieces.

  !  backup set  A proprietary RMAN backup format that contains data from one or more data files, archived redo log files, or control file or server parameter file file. See also image copy

  ✗  backup set  A backup of one or more data files, control files, server parameter file files, and archived redo log files. Each backup set consists of one or more binary files. Each binary file is called a backup piece. Backup pieces are written in a proprietary format that can only be created or restored by RMAN.  Backup sets are produced by the RMAN BACKUP command. A backup set usually consists of only one backup piece. RMAN divides the contents of a backup set among multiple backup pieces only if you limit the backup piece size using the MAXPIECESIZE option of the ALLOCATE CHANNEL or CONFIGURE CHANNEL command.

  ✗  basic table compression  A type of table compression intended for bulk load operations. You must use direct path INSERT operations, ALTER TABLE . . . MOVE operations, or online table redefinition to achieve basic table compression.

  !  big table cache  An optional, integrated portion of the database buffer cache that uses a temperature-based, object-level replacement algorithm instead of the traditional LRU-based, block-level replacement algorithm.  

  ✗  bigfile tablespace  A tablespace that contains one very large data file or temp file.  

  ✗  bind variable  A placeholder in a SQL statement that must be replaced with a valid value or value address for the statement to execute successfully. By using bind variables, you can write a SQL statement that accepts inputs or parameters at run time. The following example shows a query that uses v_empid as a bind variable: SELECT * FROM employees WHERE employee_id = :v_empid;

  ✗  bitmap index  A (database) index in which the database stores a bitmap for each index key instead of a list of rowids.  

  ✗  bitmap join index  A bitmap index for the join  of two or more tables.  

  ✗  bitmap merge  An operation that merges bitmaps retrieved from bitmap index scans. For example, if the gender and DOB columns have bitmap indexes, then the database may use a bitmap merge if the query predicate is WHERE gender='F' AND DOB > 1966.  

  !  block corruption  A data block that is not in a recognized Oracle format, or whose contents are not internally consistent.  

  ✗  block header  A part of a data block that includes information about the type of block, the address of the block, and sometimes transaction information.  

  ✗  block media recovery 

  ✗  block overhead  Space in a data block that stores metadata required for managing the block. The overhead includes the block header, table directory, and row directory.  

  ✗  branch block  In a B-tree index, a block that the database uses for searching. The leaf blocks store the index entries. The upper-level branch blocks of a B-tree index contain index data that points to lower-level index blocks.  

  !  buffer  A main memory address in the database buffer cache. A buffer caches currently and recently used data blocks read from disk. When a new block is needed, the database can replace an old data block with a new one.  

  !  buffer header  A memory structure that stores metadata about a buffer.  

  ✗  buffer cache hit ratio  The measure of how often the database found a requested block in the buffer cache without needing to read it from disk.  

  !  buffer pool  A collection of buffers in the SGA.  

  ✗  byte semantics  Treatment of strings as a sequence of bytes. Offsets into strings and string lengths are expressed in bytes.  

  ✗  cache recovery  The automatic phase of instance recovery where Oracle Database applies all committed and uncommitted changes in the online redo log files to the affected data blocks.  

  ✗  cardinality  The ratio of distinct values to the number of table rows. A column with only two distinct values in a million-row table would have low cardinality.  

  ✗  Cartesian join  A join in which one or more of the tables does not have any join conditions to any other tables in the statement. The optimizer joins every row from one data source with every row from the other data source, creating the Cartesian product of the two sets.  

  !  CDB  An Oracle Database installation that contains at least one PDB. A PDB appears to an Oracle Net client as a traditional Oracle database. Every Oracle database is either a CDB or a non-CDB.  

  !  CDB administrator  A database administrator who manages a CDB. A PDB administrator manages individual PDBs within the CDB.  

  !  CDB root  In a multitenant container database (CDB), a collection of schemas, schema objects, and nonschema objects to which all PDBs belong. Every CDB has exactly one root container, which stores the system metadata required to manage PDBs. All PDBs belong to the CDB root.  

  ✗  character encoding  A code that pairs each character from a given repertoire with a code unit to facilitate data storage.  

  ✗  character semantics  Treatment of strings as a sequence of characters. Offsets into strings and string lengths are expressed in characters (character codes).  

  ✗  character set  An encoding scheme used to display characters on your computer screen.  

  ✗  check constraint  A constraint on a column or set of columns that requires a specified condition to be true or unknown for every row.  

  !  checkpoint  1. A data structure that marks the checkpoint position, which is the SCN in the redo thread where instance recovery must begin. Checkpoints are recorded in the control file and each data file header and are a crucial element of recovery. 2. The writing of dirty data blocks in the database buffer cache to disk. The database writer (DBW) process writes blocks to disk to synchronize the buffer cache with the data files.

  !  checkpoint process (CKPT)  The background process that updates the control file and data file header with checkpoint information and signals DBW to write blocks to disk.  

  ✗  child cursor  The cursor containing the plan, compilation environment, and other information for a statement whose text is stored in a parent cursor. The parent cursor is number 0, the first child is number 1, and so on. Child cursors reference exactly the same SQL text as the parent cursor, but are different. For example, two statements with the text SELECT * FROM mytable use different cursors when they reference tables named mytable in different schemas.  

  !  circular reuse record  A type of control file record that contains noncritical information that is eligible to be overwritten if needed. When all available record slots are full, the database either expands the control file to make room for a new record or overwrites the oldest record.  

  !  clean restore point  A PDB restore point that is created when the PDB is closed. A Flashback PDB to a clean restore point does not require restoring backups or creating a temporary instance.  client In client/server architecture, the front-end database application that interacts with a user. The client portion has no data access responsibilities.  

  !  Oracle Enterprise Manager Cloud Control 

  ✗  client character set  The character set for data entered or displayed by a client application. The character set for the client and database can be different.  

  ✗  client process  A process that executes the application or Oracle tool code. When users run client applications such as SQL*Plus, the operating system creates client processes to run the applications. See also Oracle process.

  ✗  client/server architecture  Software architecture based on a separation of processing between two CPUs, one acting as the client in the transaction, requesting and receiving services, and the other as the server that provides services in a transaction.  

  ✗  cluster file system  A distributed file system that is a cluster of servers that collaborate to provide high performance service to their clients.  

  ✗  cluster index  A B-tree index on the cluster key.  

  ✗  cluster key  In a table cluster, the column or columns that the clustered tables have in common. For example, the employees and departments tables share the department_id column. Specify the cluster key when creating the table cluster and when creating every table added to the table cluster.  

  !  cold buffer  A buffer in the buffer cache that has not been recently used.  

  ✗  column  Vertical space in a table that represents a domain of data. A table definition includes a table name and set of columns. Each column has a name and data type.  

  !  columnar format  The column-based format for objects that reside in the In-Memory Column Store. The columnar format contrasts with the row format that the database uses to store objects in the database buffer cache and in data files.  

  ✗  command file (RMAN)  A file with a sequence of RMAN commands.

  ✗  commit  Action that ends a database transaction and makes permanent all changes performed in the transaction.  

  ✗  commit cleanout  The automatic removal of lock-related transaction information (ITL entry) from the blocks after a commit. The database removes the ITL entry only if modified blocks containing data from the committed transaction are still in the SGA, and if no other session is modifying them.  

  ✗  complete recovery  Recovery of one or more data files that applies all redo generated after the restored backup. Typically, you perform complete media recovery when media failure damages one or more data files or control files. You fully recover the damaged files using all redo generated since the restored backup was taken.  See Also: incomplete recovery

  ✗  complete refresh  An execution of the query that defines a materialized view. A complete refresh occurs when you initially create the materialized view, unless the materialized view references a prebuilt table, or you define the table as BUILD DEFERRED.  

  ✗  composite database operation  Activity between two points in time in a single database session.  

  ✗  composite index  An index on multiple columns in a table.  

  ✗  composite partitioning  A partitioning strategy in which a table is partitioned by one data distribution method and then each partition is further divided into subpartitions using a second data distribution method.  

  ✗  composite unique key  A set of two or more columns with a unique key constraint.  

  ✗  compound trigger  A trigger can that can fire at multiple timing points. For example, a compound trigger might fire both before and after the triggering statement.  

  ✗  compression unit  In Hybrid Columnar Compression, a logical construct that stores a set of rows. When you load data into a table, the database stores groups of rows in columnar format, with the values for each column stored and compressed together. After the database has compressed the column data for a set of rows, the database fits the data into the compression unit.  

  ✗  concatenated index  See composite index.  

  ✗  condition  The combination of one or more expressions and logical operators in a SQL statement that returns a value of TRUE, FALSE, or UNKNOWN. For example, the condition 1=1 always evaluates to TRUE.  

  ✗  conflicting write  In a read committed transaction, a situation that occurs when the transaction attempts to change a row updated by an uncommitted concurrent transaction.  

  !  connection  Communication pathway between a client process and an Oracle database instance. See also session.

  !  connection pooling  A resource utilization and user scalability feature that maximizes the number of sessions over a limited number of protocol connections to a shared server.  

  !  consistent backup  A whole database backup that you can open with the RESETLOGS option without performing media recovery. You do not need to apply redo to this backup to make it consistent. Unless you apply the redo generated since the consistent backup was created, however, you lose all transactions since the time of the consistent backup.  You can only take consistent backups after you have performed a consistent shutdown of the database. The database must not be re-opened until the backup has completed.  By its nature, a consistent backup of the whole database does not require the application of redo to be made consistent. See also inconsistent backup. See Also: fuzzy file, inconsistent backup

  !  consistent read get  The retrieval of a version of a block in the database buffer cache that is consistent to a specific SCN (part of read consistency). If the database needs a block to satisfy a query, and if no block in the database buffer cache is consistent to the correct SCN, then the database attempts to obtain the correct version of the block from undo data.  

  ✗  container  In a multitenant container database (CDB), either the root or a PDB.  

  ✗  context  A set of application-defined attributes that validates and secures an application. The SQL statement CREATE CONTEXT creates namespaces for contexts.  

  !  control file  A binary file that records the physical structure of a database and contains the names and locations of redo log files, the time stamp of the database creation, the current log sequence number, checkpoint information, and so on.  

  !  corrupt data block  

  ✗  cube  An organization of measures with identical dimensions and other shared characteristics. The edges of the cube contain the dimension members, whereas the body of the cube contains the data values.  

  !  current mode get  The retrieval of the version of a data block as it exists right now in the buffer cache, without using read consistency. Only one version of a block exists in current mode at any one time.  

  ✓  current online redo log file  The online redo log file to which the log writer (LGWR) process is actively writing.  

  ✗  cursor  A handle or name for a private SQL area in the PGA. Because cursors are closely associated with private SQL areas, the terms are sometimes used interchangeably.  

  !  data block  Smallest logical unit of data storage and organization.  One data block corresponds to a specific number of bytes of physical space on disk.

  ✗  data concurrency  Simultaneous access of the same data by many users. A multiuser database management system must provide adequate concurrency controls so that data cannot be updated or changed improperly, compromising data integrity. See also data consistency.

  ✗  data consistency  A consistent view of the data by each user in a multiuser database. See also data concurrency.

  ✗  data corruption  An error that occurs when a hardware, software, or network component causes corrupt data to be read or written.  

  !  data dictionary  A read-only collection of database tables and views containing reference information about the database, its structures, and its users.  

  ✓  data dictionary cache  A part of the shared pool which stores data dictionary information.

  ✗  data dictionary (DDL) lock  A lock that protects the definition of a schema object while an ongoing DDL operation acts on or refers to the object. Oracle Database acquires a DDL lock automatically on behalf of any DDL transaction requiring it. Users cannot explicitly request DDL locks.  

  !  data dictionary view  A predefined view of tables or other views in the data dictionary. Data dictionary views begin with the prefix DBA_, ALL_, or USER_.  

  !  data file  A physical file on disk that was created by Oracle Database and contains the data for a database. The data files can be located either in an operating system file system or Oracle ASM disk group.  

  ✗  data integrity  Business rules that dictate the standards for acceptable data. These rules are applied to a database by using integrity constraints and triggers to prevent invalid data entry.  

  ✗  data link  In a PDB, an internal mechanism that points to data (not metadata) in the root. For example, AWR data resides in the root. Each PDB uses an object link to point to the AWR data in the root, thereby making views such as DBA_HIST_ACTIVE_SESS_HISTORY and DBA_HIST_BASELINE accessible in each separate container.  

  ✗  Data-mining  The automated search of large stores of data for patterns and trends that transcend simple analysis.  

  ✗  Data Recovery Advisor  An Oracle Database tool that automatically diagnoses persistent data failures, presents repair options to the user, and executes repairs at the user's request.

  !  data segment  The segment containing the data for a nonclustered table, table partition, or table cluster. See also extent.

  ✗  data type  In SQL, a fixed set of properties associated with a column value or constant. Examples include VARCHAR2 and NUMBER. Oracle Database treats values of different data types differently.  

  ✓  data warehouse  A database optimized for querying and data analysis (OLAP) rather than for OLTP.

  ✗  database access control  Restricting data access and database activities. For example, the restriction of users from querying specified tables or executing specified database statements.  

  ✗  database application  A software program that interacts with a database to access and manipulate data.  

  !  database authentication  The process by which a user presents credentials to the database, which verifies the credentials and allows access to the database.  

  !  database block size  The data block size for a database set when it is created. The size is set for the SYSTEM and SYSAUX tablespaces and is the default for all other tablespaces. The database block size cannot be changed except by re-creating the database.  

  !  database buffer cache  The portion of the system global area (SGA) that holds copies of data blocks. All client processes concurrently connected to the database instance share access to the buffer cache.  

  ✗  database character set  A character encoding scheme that determines which languages can be represented in a database.  

  ✓  Database Configuration Assistant (DBCA)  

  ✗  database consolidation  The general process of moving data from one or more non-CDBs into a multitenant container database (CDB).  

  ✗  database driver  Software that sits between an application and an Oracle database. The driver translates the API calls made by the application into commands that the database can process. By using an ODBC driver, an application can access any data source, including data stored in spreadsheets. The ODBC driver performs all mappings between the ODBC standard and the database.  

  ✓  database failure 

  !  database instance  The combination of the SGA and background processes. An instance operates on exactly one database. Every database instance is either a read/write database instance or a read-only database instance. In an Oracle Real Application Clusters configuration, multiple instances access a single database.  

  ✗  database link  A schema object in one database that enables users to access objects in a different database.  

  ✗  database management system (DBMS)  Software that controls the storage, organization, and retrieval of data.  

  ✗  database object  An object in the database that can be manipulated with SQL. Schema objects such as tables and indexes reside in schemas. Nonschema objects such as directories and roles do not reside in schemas.  

  ✗  database operation  In the context of database monitoring, a logical entity that includes a SQL statement, a PL/SQL block, or a composite of the two.  

  !  database point-in-time recovery  A type of media recovery that results in a noncurrent version of the database. In this case, you do not apply all of the redo generated after the restored backup.  

  ✗  database point-in-time recovery (DBPITR)  The recovery of an entire database to a specified past target time, SCN, or log sequence number.  See Also: incomplete recovery, tablespace point-in-time recovery (TSPITR)

  !  database security  The aspect of database administration that involves user authentication, encryption, access control, and monitoring.  

  ✗  database server  A server that reliably manages a large amount of data in a multiuser environment so that users can concurrently access the same data. A database server also prevents unauthorized access and provides efficient solutions for failure recovery.  

  !  Database Server Grid  A collection of commodity servers connected together to run on one or more databases

  !  Database Storage Grid  A collection of low-cost modular storage arrays combined together and accessed by the computers in the Database Server Grid.  

  !  database service  A named representation of one or more database instances. The service name for an Oracle database is normally its global database name. Clients use the service name to connect to one or more database instances.  

  ✗  database user  An account through which you can log in to an Oracle database.  

  ✗  database writer (DBW)  A background process that writes buffers in the database buffer cache to data files.  

  ✗  DDL  Data definition language. Includes statements such as CREATE TABLE or ALTER INDEX that define or change a data structure.  

  ✗  deadlock  A situation in which two or more users are waiting for data locked by each other. Such deadlocks are rare in Oracle Database.  

  ✗  declarative language  A nonprocedural language that describes what should be done, now how to do it. SQL and Prolog are examples of declarative languages. SQL is declarative in the sense that users specify the result that they want, not how to derive it.  

  !  dedicated server  A database configuration in which a server process handles requests for a single client process.  See also shared server.

  ✗  deferrable constraint  A constraint that permits a SET CONSTRAINT statement to defer constraint checking until a COMMIT statement is issued. A deferrable constraint enables you to disable the constraint temporarily while making changes that might violate the constraint.  

  ✗  deferred insert  An insert with the MEMOPTIMIZE_WRITE hint into a table specified as MEMOPTIMIZE FOR WRITE. Deferred inserts cannot be rolled back and do not use the consistency mechanisms of the database buffer cache. Background processes write deferred inserts to the data files asynchronously.  definer's rights PL/SQL procedure A procedure that executes with the privileges of its owner, not its current user.  

  ✗  degree of parallelism  The number of parallel execution servers associated with a single operation. Parallel execution is designed to effectively use multiple CPUs. Oracle Database parallel execution framework enables you to either explicitly choose a specific degree of parallelism or to rely on Oracle Database to automatically control it.  

  ✗  dependent object  In a schema object dependency, the object whose definition references another object. For example, if the definition of object A references object B, then A is a dependent object on B.  

  ✗  descending index  An index in which data is stored on a specified column or columns in descending order.  

  ✗  dimension  A structure that categorizes data to enable users to answer business questions. Commonly used dimensions are customers, products, and time.  

  ✗  dimension table  A relational table that stores all or part of the values for a dimension in a star or snowflake schema. Dimension tables typically contain columns for the dimension keys, levels, and attributes.  

  ✗  directory object  A database object that specifies an alias for a directory on the server file system where external binary file LOBs (BFILEs) and external table data are located. All directory objects are created in a single namespace and are not owned by an individual schema.  

  !  direct path insert  An insert in which the database writes data directly to the data files, bypassing the database buffer cache. The database appends the inserted data to the existing data in the table.  

  !  direct path read  A single or multiblock read into the PGA, bypassing the SGA.  

  !  dirty read  The situation that occurs when a transaction reads uncommitted data written by another transaction. Oracle Database never permits dirty reads.  

  ✗  dispatcher  See dispatcher process (Dnnn).  

  ✗  dispatcher process (Dnnn)  Optional background process present only when a shared server configuration is used. Each dispatcher process is responsible for routing requests from connected client processes to available shared server processes and returning the responses.  

  !  distributed database  A set of databases in a distributed system that can appear to applications as a single data source.  

  ✗  distributed environment  A network of disparate systems that seamlessly communicate with each other.  

  ✗  distributed processing  The operations that occur when an application distributes its tasks among different computers in a network.  

  ✗  distributed transaction  A transaction that includes statements that, individually or as a group, update data on nodes of a distributed database. Oracle Database ensures the integrity of data in distributed transactions using the two-phase commit mechanism.  

  ✗  DML  Data manipulation language. Includes statements such as SELECT, INSERT, UPDATE, and DELETE.  

  ✗  DML lock  A lock that prevents destructive interference of simultaneous conflicting DML or DDL operations. DML statements automatically acquire row locks and table locks.  

  !  dynamic performance view  A special views that is continuously updated while a database is open and in use. The dynamic performance views are sometimes called V$ views.  

  ✗  dynamic SQL  SQL whose complete text is not known until run time. Dynamic SQL statements are stored in character strings that are entered into, or built by, the program at run time.  

  !  edition  A private environment in which you can redefine database objects. Edition-based redefinition enables you to upgrade an application's database objects while the application is in use, thus minimizing or eliminating downtime.  

  ✗  encryption  The process of transforming data into an unreadable format using a secret key and an encryption algorithm.  

     EPG  Embedded PL/SQL Gateway

  ✗  equijoin  A join with a join condition containing an equality operator.  

  !  ETL  Extraction, transformation and loading: The process of loading data from source systems into a data warehouse

  ✗  exclusive lock  A lock that prevents the associated resource from being shared. The first transaction to obtain an exclusive lock on a resource is the only transaction that can alter the resource until the lock is released.  

  ✗  executable SQL statement  A SQL statement that generates calls to a database instance, including DML and DDL statements and the SET TRANSACTION statement.  

  ✗  Execution plan  The combination of steps used by the database to execute a SQL statement. Each step either retrieves rows of data physically from the database or prepares them for the user issuing the statement. You can override execution plans by using a hint.

  ✗  expression  A combination of one or more values, operators, and SQL functions that resolves to a value. For example, the expression 2*2 evaluates to 4. In general, expressions assume the data type of their components.  

  ✗  extent  Multiple contiguous data blocks allocated for storing a specific type of information. A segment is made up of one or more extents.

  ✗  external table  A read-only table whose metadata is stored in the database but whose data in stored in files outside the database. The database uses the metadata describing external tables to expose their data as if they were relational tables.  

  ✗  fact  Data that represents a business measure, such as sales or cost data.  

  ✗  fact table  A table in a star schema of a data warehouse that contains factual data. A fact table typically has two types of columns: those that contain facts and those that are foreign keys to dimension tables.  

  ✗  fast full index scan  A full index scan in which the database reads all the blocks in the index using multiblock reads, and then discards the branch blocks, returning the index blocks in no particular order.  

  !  fast recovery area  An optional disk location that stores recovery-related files such as control file and online redo log copies, archived redo log files, flashback logs, and RMAN backups.  

  ✗  fast recovery area  An optional disk location that you can use to store recovery-related files such as control file and online redo log copies, archived redo log files, flashback logs, and RMAN backups. Oracle Database and RMAN manage the files in the fast recovery area automatically. You can specify the disk quota, which is the maximum size of the fast recovery area.

  ✗  fault tolerance  The protection provided by a high availability architecture against the failure of a component in the architecture.  

  ✗  field  In a table, the intersection of a row and column.  

  ✗  file system  A data structure built inside a contiguous disk address space.  

  ✗  fine-grained auditing  A type of database auditing that enables you to audit specific table columns, and to associate event handlers during policy creation.  

  !  fixed SGA  An internal housekeeping area that contains a variety of information, including general information about the state of the database and the instance, and information communicated between processes.  

  !  flashback data archive process (FBDA)  The background process that archives historical rows of tracked tables into flashback data archive. When a transaction containing DML on a tracked table commits, this process stores the pre-image of the changed rows into the flashback data archive. It also keeps metadata on the current rows.  

  ✗  force full database caching mode  The caching mode that is manually enabled by executing the ALTER DATABASE ... FORCE FULL DATABASE CACHING statement. Unlike in the default caching mode, Oracle Database caches the entire database, LOBs specified with the NOCACHE attribute.  

  ✗  foreign key  An integrity constraint that requires each value in a column or set of columns to match a value in the unique or primary key for a related table. Integrity constraints for foreign keys define actions dictating database behavior if referenced data is altered.  

  ✗  foreign key constraint  A constraint in which Oracle Database enforces the relationship between two tables that contain one or more common columns. The constraint requires that for each value in the column on which the constraint is defined, the value in the other specified other table, and column must match. For example, a referential integrity rule might state that an employee can only work for an existing department.  

  ✗  format model  A character literal that describes the format of a datetime in a character string.  

  !  free list  A linked list to manage free space in a segment in manual segment space management (MSSM). For a database object that has free space, a free list keeps track of blocks under the high water mark. As blocks are used, the database puts blocks on or removes blocks from the free list as needed.  

  ✗  full index scan  An index scan in which the database reads only the root and left side branch blocks to find the first leaf block, and then reads the leaf blocks in index sorted order using single block I/O.  

  ✗  full outer join  A join between two tables that returns the result of an inner join and the result of a left outer join and a right outer join.  

  ✗  full table scan  A scan of table data in which the database sequentially reads all rows from a table and filters out those that do not meet the selection criteria. The database scans all formatted data blocks under the high water mark (HWM).  

  ✗  function  A schema object, similar to a PL/SQL procedure, that always returns a single value.  

  ✗  function-based index  An index that computes the value of a function or expression involving one or more columns and stores it in the index.  

  ✗  GDS  See Global Data Services (GDS) 

  ✗  GDS catalog  A metadata repository, located inside an Oracle database, that is associated with a GDS configuration. Every cloud has one and only one catalog.  

  ✗  GDS configuration  A set of databases integrated by the GDS framework into a single virtual server that offers one or more global services while ensuring high performance, availability, and optimal utilization of resources. See also global service.

  ✗  GDS pool  A set of databases within a GDS configuration that provides a unique set of global services and belongs to a specific administrative domain.  

  ✗  GDS region  A logical boundary within a GDS configuration that contains database clients and servers that are geographically close to each other.  

  ✗  Global Data Services (GDS)  An automated workload management solution for replicated databases. Database services are named representations of one or more database instances. GDS implements the Oracle Database service model across a set of replicated databases.  

  !  global database name  The combination of the database name (DB_NAME) and network domain (DB_DOMAIN), for example, orcl.example.com. The global database domain is unique within a network.  

  ✗  global partitioned index  A B-tree index that is partitioned independently of the partitioning scheme used on the indexed table. A single index partition can point to any or all table partitions.  

  ✗  global service  A database service provided by multiple databases synchronized through data replication.  

  ✗  global service manager  The central management tool in the Global Data Services framework. At least one global service manager must exist in every GDS region of a GDS configuration.  

  ✗  global temporary table  A special temporary table that stores intermediate session-private data for a specific duration.  

  !  granule  The basic unit of work in parallelism. Oracle Database divides the operation executed in parallel (for example, a table scan, table update, or index creation) into granules. Parallel execution processes execute the operation one granule at a time.  

  ✗  grid computing  A computing architecture that coordinates large numbers of servers and storage to act as a single large computer.  

  !  grid infrastructure  The software that provides the infrastructure for an enterprise grid architecture. In a cluster, this software includes Oracle Clusterware and Oracle ASM. For a standalone server, this software includes Oracle ASM. Oracle Database combines these products into one software installation called the Grid home.  

  !  hard parse  The steps performed by the database to build a new executable version of application code. The database must perform a hard parse instead of a soft parse if the parsed representation of a submitted statement does not exist in the shared pool.  

  ✗  hash cluster  A type of table cluster that is similar to an indexed cluster, except the index key is replaced with a hash function. No separate cluster index exists. In a hash cluster, the data is the index.  

  ✗  hash collision  Hashing multiple input values to the same output value.  

  ✗  hash function  A function that operates on an arbitrary-length input value and returns a fixed-length hash value.  

  ✗  hash index  An internal structure in the memoptimize pool that indexes a memory area by primary key.

  ✗  hash join  A join in which the database uses the smaller of two tables or data sources to build a hash table in memory. The database scans the larger table, probing the hash table for the addresses of the matching rows in the smaller table.  

  ✗  hash key value  In a hash cluster, an actual or possible value inserted into the cluster key column. For example, if the cluster key is department_id, then hash key values could be 10, 20, 30, and so on.  

  ✗  hash partitioning  A partitioning strategy that maps rows to partitions based on a hashing algorithm that the database applies to the user-specified partitioning key. The destination of a row is determined by the internal hash function applied to the row by the database. The hashing algorithm is designed to distribute rows evenly across devices so that each partition contains about the same number of rows.  

  ✗  hash table  An in-memory data structure that associates join keys with rows in a hash join. For example, in a join of the employees and departments tables, the join key might be the department ID. A hash function uses the join key to generate a hash value. This hash value is an index in an array, which is the hash table.  

  ✗  hash value  In a hash cluster, a unique numeric ID that identifies a bucket. Oracle Database uses a hash function that accepts an infinite number of hash key values as input and sorts them into a finite number of buckets. Each hash value maps to the database block address for the block that stores the rows corresponding to the hash key value (department 10, 20, 30, and so on).  

  ✗  hashing  A mathematical technique in which an infinite set of input values is mapped to a finite set of output values, called hash values. Hashing is useful for rapid lookups of data in a hash table.  

  ✗  heap-organized table  A table in which the data rows are stored in no particular order on disk. By default, CREATE TABLE creates a heap-organized table.  

  ✗  hierarchical database  A database that organizes data in a tree structure. Each parent record has one or more child records, similar to the structure of a file system.  

  !  high water mark (HWM)  The boundary between used and unused space in a segment.  

  !  hint  An instruction passed to the optimizer through comments in a SQL statement. The optimizer uses hints to choose an execution plan for the statement.  

  !  hot buffer  A buffer in the database buffer cache that is frequently accessed and has been recently used.  

  !  human error outage  An outage that occurs when unintentional or malicious actions are committed that cause data in the database to become logically corrupt or unusable.  

  ✗  Hybrid Columnar Compression  A hybrid method that uses row and columnar techniques to compress data in a data block. A logical construct called a compression unit is used to store a set of hybrid columnar-compressed rows.

  ✗  hybrid partitioned table  A table in which some partitions are stored in data file segments and some are stored in external data source.

     ILM  Information Lifecycle Management

  !  IM column store  An optional SGA area that stores copies of tables and partitions in a columnar format optimized for rapid scans.

  !  image copy  A bitwise exact duplate of a data file, control file, or archived redo log file. See also backup set.

  ✗  implicit query  A component of a DML statements that retrieves data without a subquery. An UPDATE, DELETE or MERGE statement that does not explicitly include a SELECT statement uses an implicit query to retrieve the rows to be modified.

  ✗  in-doubt distributed transaction  A distributed transaction in which a two-phase commit is interrupted by any type of system or network failure.  

  ✗  in-flight transaction  A transaction that is running when an outage breaks the connection between a client application and the database.  

  !  In-Memory Column Store  See IM column store.  

  !  inactive online redo log file  An online redo log file that is not required for instance recovery

  ✗  incomplete recovery  A synonym for database point-in-time recovery (DBPITR).  See Also: complete recovery, media recovery, recover

  !  inconsistent backup  A backup in which some files in the backup contain changes made after the checkpoint. Unlike a consistent backup, an inconsistent backup requires media recovery to be made consistent.  

  !  incremental backup  Only blocks that changed since the last backup are copied.

  !  incremental-forever backup strategy  The strategy in which an initial level 0 backup is taken to the Recovery Appliance, with all subsequent incremental backups occurring at level 1. The Recovery Appliance creates a virtual full backup by combining the initial level 0 with subsequent level 1 backups.  

  ✗  incremental refresh  A refresh that processes only the changes to the existing data in a materialized view. This method eliminates the need for a complete refresh.  

  ✗  index  Optional schema object associated with a nonclustered table, table partition, or table cluster. In some cases indexes speed data access.  

  !  index block  A special type of data block that manages space differently from table blocks.  

  ✗  index cluster  An table cluster that uses an index to locate data. The cluster index is a B-tree index on the cluster key.  

  ✗  index clustering factor  A measure of the row order in relation to an indexed value such as last name. The more order that exists in row storage for this value, the lower the clustering factor.  

  ✗  index-organized table  A table whose storage organization is a variant of a primary B-tree index. Unlike a heap-organized table, data is stored in primary key order.  

  ✗  index range scan  An ordered scan of an index that has the following characteristics: One or more leading columns of an index are specified in conditions. A condition specifies a combination of one or more expressions and logical (Boolean) operators and returns a value of TRUE, FALSE, or UNKNOWN. 0, 1, or more values are possible for an index key.

  ✗  index scan  The retrieval of a row by traversing an index, using the indexed column values specified by the statement.  

  ✗  index segment  A segment that stores data for a nonpartitioned index or index partition.  

  ✗  index skip scan  An index scan that uses logical subindexes of a composite index. The database "skips" through a single index as if it were searching separate indexes.  

  ✗  index unique scan  An index scan that must have either 0 or 1 rowid associated with an index key. The database performs a unique scan when a predicate references all of the columns in the key of a UNIQUE index using an equality operator.  

  ✗  information system  A formal system for storing and processing information.  

  !  initialization parameter  Init parameters are configuration parameters that control the operation of an instance. Settings for initialization parameters are stored in a text-based initialization parameter file or binary server parameter file.

  !  initialization parameter file  A text file that contains initialization parameter settings for a database instance.  

  ✗  inner join  A join of two or more tables that returns only those rows that satisfy the join condition.  

  !  instance failure  The termination of a database instance because of a hardware failure, Oracle internal error, or SHUTDOWN ABORT statement.  

  !  instance PGA  The collection of individual PGAs in a database instance.  

  !  instance recovery  The automatic application of redo log records to uncommitted data blocks when an database instance is restarted after a failure.  

  ✗  INSTEAD OF trigger  A trigger that is fired by Oracle Database instead of executing the triggering statement. These triggers are useful for transparently modifying views that cannot be modified directly through DML statements.  

  ✗  integrity  See data integrity.  

  ✗  integrity constraint  Declarative method of defining a rule for a column. The integrity constraints enforce business rules and prevent the entry of invalid information into tables.  

  !  interested transaction list (ITL)  Information in a block header that determines whether a transaction was uncommitted when the database began modifying the block. Entries in the ITL describe which transactions have rows locked and which rows in the block contain committed and uncommitted changes.  

  ✗  interval partition  An extension of range partitioning that instructs the database to create partitions of the specified range or interval. The database automatically creates the partitions when data inserted into the table exceeds all existing range partitions.  

  ✗  invisible index  An index that is maintained by DML operations, but is not used by default by the optimizer. Making an index invisible is an alternative to making it unusable or dropping it.  

  ✗  invoker's rights PL/SQL procedure  A procedure that executes in the current user's schema with the current user's privileges.  

  ✗  Java pool  An area of memory that stores all session-specific Java code and data within the Java Virtual Machine (JVM).  

  ✗  Java stored procedure  A Java method published to SQL and stored in the database.  

  ✗  JavaScript Object Notation (JSON)  A language-independent, text-based data format that can represent objects, arrays, and scalar data.  JavaScript object An associative array of zero or more pairs of property names and associated JavaScript Object Notation (JSON) values.  

  ✗  job queue process  An optional background process that runs user jobs, often in batch mode. A job is a user-defined task scheduled to run one or more times.  

  ✗  join  A statement that retrieves data from multiple tables specified in the FROM clause. Join types include inner joins, outer joins, and Cartesian joins.  

  ✗  join attribute clustering  In an attribute-clustered table, clustering that is based on joined columns.  

  ✗  join condition  A condition that compares two columns, each from a different table, in a join. The database combines pairs of rows, each containing one row from each table, for which the join condition evaluates to TRUE.  

  ✗  join view  A view whose definition includes multiple tables or views in the FROM clause.  

  ✗  JSON object  A JavaScript object literal written as a property listed enclosed in braces.  See also JavaScript Object Notation (JSON).  

  ✗  JVM  A virtual processor that runs compiled Java code.  

  ✗  key  Column or set of columns included in the definition of certain types of integrity constraints.  

  ✗  key compression  See prefix compression.  

  ✗  key-preserved table  In a join query, a table in which each row appears at most one time in the output of the query.  

  ✗  key compression  Alternative name for prefix compression.  

  ✗  key values  Individual values in a key.  

  ✗  large object (LOB)  See LOB.  

  ✗  large pool  Optional area in the SGA that provides large memory allocations for backup and restore operations, I/O server processes, and session memory for the shared server and Oracle XA.  

  ✗  latch  A low-level serialization control mechanism used to protect shared data structures in the SGA from simultaneous access.  

  ✗  latch sleeping  The phenomenon that occurs when a process releases the CPU before renewing the latch request.  

  ✗  latch spinning  The phenomenon that occurs when a process repeatedly requests a latch in a loop.  

  ✗  leaf block  In a B-tree index, a lower-level block that stores index entries. The upper-level branch blocks of a B-tree index contain index data that points to lower-level index blocks.  

  ✗  left outer join  The result of a left outer join for table A and B contains all records of the left table A, even if the join condition does not match a record in the right table B. For example, if you perform a left outer join of employees (left) to departments (right), and if some employees are not in a department, then the query returns rows from employees with no matches in departments.  

  ✗  library cache  An area of memory in the shared pool. This cache includes the shared SQL areas, private SQL areas (in a shared server configuration), PL/SQL procedures and packages, and control structures such as locks and library cache handles.  

  ✗  list partitioning  A partitioning strategy that uses a list of discrete values as the partition key for each partition. You can use list partitioning to control how individual rows map to specific partitions. By using lists, you can group and organize related sets of data when the key used to identify them is not conveniently ordered.  

  !  listener  A process that listens for incoming client connection requests and manages network traffic to the database.  

  !  listener registration process (LREG)  The process that registers information about the database instance and dispatcher processes with the Oracle Net listener.  

  ✗  literal  A fixed data value.  

  ✗  LOB  Large object. Large Objects include the following SQL data types: BLOB, CLOB, NCLOB, and BFILE. These data types are designed for storing data that is large in size.  

  ✗  local partitioned index  An index partitioned on the same columns, with the same number of partitions and the same partition bounds as its table. A one-to-one parity exists between index partitions and table partitions.  

  ✗  local temporary tablespace  A temporary tablespace that resides on local storage and is accessible by a specific database instance. In contrast, a shared shared temporary tablespace resides on shared storage and is accessible by all database instances.  local undo mode The use of a separate set of undo data files for each PDB in a CDB.  

  ✗  locale  Within the context of globalization support, a linguistic and cultural environment in which a system or program is running.  

  ✗  locally managed tablespace  A tablespace that uses a bitmap stored in each data file to manage the extents. In contrast, a dictionary-managed tablespace uses the data dictionary to manage space.  

  ✗  lock  A database mechanism that prevents destructive interaction between transactions accessing a shared resource such as a table, row, or system object not visible to users. The main categories of locks are DML locks, DDL locks, and latches and internal locks.  

  ✗  lock conversion  The automatic conversion of a table lock of lower restrictiveness to one of higher restrictiveness. For example, suppose a transaction issues a SELECT ... FOR UPDATE for an employee and later updates the locked row. In this case, the database automatically converts the row share table lock to a row exclusive table lock.  

  ✗  lock escalation  A situation that occurs in some databases when numerous locks are held at one level of granularity (for example, rows) and the database raises the locks to a higher level of granularity (for example, table). Oracle Database never escalates locks.  

  ✗  log sequence number  A number that uniquely identifies a set of redo records in a redo log file. When the database fills one online redo log file and switches to a different one, the database automatically assigns the new file a log sequence number.  

  ✗  log switch  The point at which the log writer process (LGWR) stops writing to the active redo log file and switches to the next available redo log file. LGWR switches when either the active redo log file is filled with redo records or a switch is manually initiated.  

  ✗  log writer process (LGWR)  The background process responsible for redo log buffer management—writing the redo log buffer to the online redo log. LGWR writes all redo entries that have been copied into the buffer since the last time it wrote.  

  ✗  logical  

  !  Logical Flashback Features  The set of Oracle Flashback Technology features other than Oracle Flashback Database. The logical features enable you to view or rewind individual database objects or transactions to a past time.

  !  logical I/O  Reads and writes of buffers in the database buffer cache.  

  !  logical read  A read of a buffer in the database buffer cache.  

  ✗  logical rowid  A rowid for an index-organized table. A logical rowid is a base64-encoded representation of a table primary key.  

  ✗  logical transaction ID  A globally unique identifier that defines a transaction from the application perspective. The logical transaction ID is bound to the database transaction ID.  

  ✗  logical volume  A virtual disk partition.  

  ✗  logical volume manager (LVM)  A software package, available with most operating systems, that enables pieces of multiple physical disks to be combined into a single contiguous address space that appears as one disk to higher layers of software.  

  ✗  lookup table  A table containing a code column and an associated value column. For example, a job code corresponds to a job name. In contrast to a master table in a pair of master-detail tables, a lookup table is not the means to obtain a detailed result set, such as a list of employees. Rather, a user queries a table such as employees for an employee list and then joins the result set to the lookup table.  

  ✗  lost update  A data integrity problem in which one writer of data overwrites the changes of a different writer modifying the same data.  

  ✗  lost write  A data corruption that occurs when the database thinks that it has written a block to persistent storage, but the block either was not written, or a previous version of the block was written.  

  ✗  manageability monitor process (MMON)  The background process that performs many tasks related to the Automatic Workload Repository (AWR). For example, MMON writes when a metric violates its threshold value, taking snapshots, and capturing statistics value for recently modified SQL objects.  

  ✗  mantissa  The part of a floating-point number that contains its significant digits.  

  ✗  manual segment space management (MSSM)  A legacy space management method that uses a linked list called a free list to manage free space in a segment.  

  ✗  manual undo management mode  A mode of the database in which undo blocks are stored in user-managed undo segments. In automatic undo management mode, undo blocks are stored in a system-managed, dedicated undo tablespace.  

  !  master database  In replication, the source of the data that is copied to a subscriber database. The replication agent on the master database reads the records from the transaction log for the master database. It forwards changes to replicated elements to the replication agent on the subscriber database. The replication agent on the subscriber database then applies the updates.  

  ✗  master-detail tables  A detail table has a foreign key relationship with a master table. For example, the employees detail table has a foreign key to the departments master table. Unlike a lookup table, a master table is typically queried and then joined to the detail table. For example, a user may query a department in the departments table and then use this result to find the employees in this department.  

  !  master site  In a replication environment, a different database with which a materialized view shares data.  

  !  master table  In a replication environment, the table associated with a materialized view at a master site.  

  ✗  materialized view  A schema object that stores the result of a query. The FROM clause of the query can name tables, views, and other materialized views. See also view.

  !  media recovery  The application of redo or incremental backups to a data block or backup data file.  

  !  media management software 

  !  memoptimize pool  An SGA pool that stores buffers and related structures for heap-organized tables specified as MEMOPTIMIZE FOR READ.  metadata link In a PDB, an internal mechanism that points to a dictionary object definition stored in the root. For example, the OBJ$ table in each PDB uses a metadata link to point to the definition of OBJ$ stored in the root.  

  ✗  metric  The rate of change in a cumulative statistic 

  !  mounted database  A database instance that is started and has the database control file open.  

  !  multitenant architecture  The architecture that enables an Oracle database to function as a multitenant container database (CDB), which means that it can contain multiple PDBs. A PDB is a portable collection of schemas, schema objects, and nonschema objects that appears to an Oracle Net client as a traditional Oracle database (non-CDB).  

  ✗  multitenant container database (CDB)  See CDB.  

  ✗  multithreaded Oracle Database model  A model that enables Oracle processes to execute as operating system threads in separate address spaces. In threaded mode, some background processes on UNIX and Linux run as processes containing one thread, whereas the remaining Oracle processes run as threads within processes.  

  ✗  multitier architecture  An architecture in which one or more application servers provide data for clients and serves as an interface between clients and database servers.  

  ✗  multiversion consistency model  A model that enables the database to present a view of data to multiple concurrent users, with each view consistent to a point in time.  

  !  multiversioning  The ability of the database to simultaneously materialize multiple versions of data.  

  ✗  mutual exclusion object (mutex)  A low-level mechanism that prevents an object in memory from aging out or from being corrupted when accessed by concurrent processes.  

  ✗  natural key  A meaningful identifier made of existing attributes in a table. For example, a natural key could be a postal code in a lookup table.  

  ✗  network database  A type of database, similar to a hierarchical database, in which records have a many-to-many rather than a one-to-many relationship.  

  ✗  network encryption  Encrypting data as it travels across the network between a client and server.  

  ✗  non-CDB  An Oracle database that is not a multitenant container database (CDB). Before Oracle Database 12c, all databases were non-CDBs. Starting in Oracle Database 12c, every database must be either a CDB or a non-CDB.  

  !  noncircular reuse record  A control file record that contains critical information that does not change often and cannot be overwritten. Examples of information include tablespaces, data files, online redo log files, and redo threads. Oracle Database never reuses these records unless the corresponding object is dropped from the tablespace.  

  ✗  nondeferrable constraint  A constraint whose validity check is never deferred to the end of the transaction. Instead, the database checks the constraint at the end of each statement. If the constraint is violated, then the statement rolls back.  

  ✗  null  Absence of a value in a column of a row. Nulls indicate missing, unknown, or inapplicable data.  

  ✗  object-relational database management system (ORDBMS)  An RDBMS that implements object-oriented features such as user-defined types, inheritance, and polymorphism.  

  ✗  object table  An special kind of table in which each row represents an object.  

  ✗  object type  A schema object that abstracts a real-world entity such as a purchase order. Attributes model the structure of the entity, whereas methods implement operations an application can perform on the entity.  

  ✗  object view  A virtual object table. Each row in the view is an object, which is an instance of a user-defined data type.  

  ✗  OLAP  Online Analytical Processing. OLAP is characterized by dynamic, dimensional analysis of historical data.  

  ✗  OLAP page pool  The pool in the UGA that manages OLAP data pages, which are equivalent to data blocks. The page pool is allocated at the start of an OLAP session and released at the end of the session.  

  ✗  OLTP  Online Transaction Processing. OLTP systems are optimized for fast and reliable transaction handling. Compared to data warehouse systems, most OLTP interactions involve a relatively small number of rows, but a larger group of tables.  

  !  online redo log  The set of two or more online redo log files that record all changes made to Oracle Database data files and control file. When a change is made to the database, Oracle Database generates a redo record in the redo buffer. The log writer process (LGWR) process writes the contents of the redo log buffer to the online redo log.  

  !  online redo log group  An online redo log file and its redundant copies.  

  ✗  operating system block  The minimum unit of data that the operating system can read or write.  

  ✗  operator  1. In memory management, operators control the flow of data. Examples include sort, hash join, and bitmap merge operators. 2. In SQL, an operator manipulates data items called operands or arguments and returns a result. Keywords or special characters represent the operators. For example, an asterisk (*) represents the multiplication operator.

  ✗  optimizer  Built-in database software that determines the most efficient way to execute a SQL statement by considering factors related to the objects referenced and the conditions specified in the statement.  

  ✗  optimizer statistics  Details about the database its object used by the optimizer to select the best execution plan for each SQL statement.

  ✗  Oracle architecture  Memory and process structures used by Oracle Database to manage a database.  

  ✗  Oracle Application Express  A Web application development tool for Oracle Database. Oracle Application Express uses built-in features such as user interface themes, navigational controls, form handlers, and flexible reports to accelerate application development.  

  !  Oracle Automatic Storage Management (Oracle ASM)  See Oracle ASM.  

  !  Oracle ASM  Oracle Automatic Storage Management (Oracle ASM). A volume manager and a file system for database files. Oracle ASM is Oracle's recommended storage management solution, providing an alternative to conventional volume managers and file systems.  

  !  Oracle ASM allocation unit  The fundamental unit of allocation within an ASM disk group. An allocation unit is the smallest contiguous disk space that Oracle ASM allocates. One or more allocation units form an Oracle ASM extent.  

  !  Oracle ASM disk  A storage device that is provisioned to an Oracle ASM disk group. An Oracle ASM disk can be a physical disk or partition, a Logical Unit Number (LUN) from a storage array, a logical volume, or a network-attached file.  

  !  Oracle ASM disk group  One or more Oracle ASM disks managed as a logical unit. I/O to a disk group is automatically spread across all the disks in the group.  

  !  Oracle ASM extent  A section of an Oracle ASM file. An Oracle ASM file consists of one or more file extents. Each Oracle ASM extent consists of one or more allocation units on a specific disk.  

  !  ASM file  A file stored in an Oracle ASM disk group. The database can store data files, control file, online redo log files, and other types of files as Oracle ASM files.  

  !  Oracle ASM instance  A special Oracle instance that manages Oracle ASM disks. Both the Oracle ASM instance and the database instances require shared access to the disks in an Oracle ASM disk group. Oracle ASM instances manage the metadata of the disk group and provide file layout information to the database instances.  

  !  Oracle base  The Oracle base directory is the database home directory for Oracle Database installation owners. The directory, which is specified by the ORACLE_BASE environment variable, is the root of the Oracle directory tree.  Oracle base configuration directory A directory that contains the instance-specific configuration files.  For a read-write Oracle home, the Oracle base home (ORACLE_BASE_HOME), Oracle base configuration directory (ORACLE_BASE_CONFIG), and Oracle home are the same. For a read-only Oracle home, the Oracle base configuration directory contains configuration files shared by all Oracle homes in an Oracle base home. To prevent naming collisions, each file name contains the SID (system identifier).  

  !  Oracle base home  A directory that stores configuration files for the database instances associated with an Oracle home.  For a read-write Oracle home, the Oracle base home (ORACLE_BASE_HOME), Oracle base configuration directory (ORACLE_BASE_CONFIG), and Oracle home are the same. For a read-only Oracle home, the Oracle base home is a home-specific directory located in the homes/home_name subdirectory of the Oracle base.  

  !  Oracle Clusterware  A set of components that enables servers to operate together as if they were one server. Oracle Clusterware is a requirement for using Oracle RAC and it is the only clusterware that you need for platforms on which Oracle RAC operates.  

  ✗  Oracle Connection Manager  A router through which a client connection request may be sent either to its next hop or directly to the database server.  

  !  Oracle database  A set of files, located on disk, that store data. Because a database instance and a database are so closely connected, the term Oracle database is often used to refer to both instance and database.  

  ✗  Oracle Database Vault  A database security feature that controls when, where, and how databases, data, and applications are accessed.  

  !  Oracle Data Redaction  A feature of Oracle Advanced Security that enables you to mask (redact) data that is queried by low-privileged users or applications.  

  ✗  Oracle Developer Tools for Visual Studio .NET  A set of application tools integrated with the Visual Studio .NET environment. These tools provide GUI access to Oracle functionality, enable the user to perform a wide range of application development tasks, and improve development productivity and ease of use.  

  ✗  Oracle Enterprise Manager  A system management tool that provides centralized management of an Oracle database environment.  

  !  Oracle Flashback Technology  A group of features that supports viewing past states of data, and winding data back and forth in time, without needing to restore backups.  

  !  Oracle Flashback Technology  A set of Oracle Database features that provide an additional layer of data protection. These features include Oracle Flashback Query, Oracle Flashback Version Query, Oracle Flashback Transaction Query, Oracle Flashback Transaction, Oracle Flashback Table, Oracle Flashback Drop, and Oracle Flashback Database. You can use flashback features to view past states of data and rewind parts or all of your database. In general, flashback features are more efficient and less disruptive than media recovery in most situations in which they apply.

  ✗  Oracle Flex Clusters  A large cluster configured using Oracle Clusterware and Oracle Real Application Clusters. These clusters contain two types of nodes arranged in a hub-and-spoke architecture: Hub Nodes and Leaf Nodes.  

  ✗  Oracle Globalization Development Kit (GDK)  A development toolkit that includes comprehensive programming APIs for both Java and PL/SQL, code samples, and documentation that address many of the design, development, and deployment issues encountered while creating global applications.  

  !  Oracle home  The operating system location of an Oracle Database installation. An Oracle home can be read/write or read-only.  

  ✗  Oracle JDeveloper  An integrated development environment (IDE) for building service-oriented applications using the latest industry standards for Java, XML, Web services, and SQL.  

  ✗  Oracle JVM  A standard, Java-compatible environment that runs any pure Java application.  

  !  Oracle managed files (OMF)  A database file naming strategy that enables database administrators to specify operations in terms of database objects rather than file names. Oracle Managed Files eliminates the need for administrators to directly manage the operating system files in a database.  

  ✗  Oracle managed file  A database file managed by the Oracle Managed Files feature.

  ✗  Oracle Managed Files (OMF)  A service that automates naming, location, creation, and deletion of database files.

  !  Oracle Multitenant  A database option that enables you to create multiple PDBs in a CDB.  

  !  Oracle Net  Communication software that enables a network session between a client application and an Oracle database. After a network session is established, Oracle Net acts as a data courier for the client application and the database.  

  !  Oracle Net Listener  A process that resides on the server whose responsibility is to listen for incoming client connection requests and manage the traffic to the server. When a client requests a network session with a database, Oracle Net Listener (typically called the listener) receives the request. If the client information matches the listener information, then the listener grants a connection to the database server.  

  !  Oracle Net Services  A suite of networking components that provide enterprise-wide connectivity solutions in distributed, heterogeneous computing environments. Oracle Net Services includes Oracle Net, listener, Oracle Connection Manager, Oracle Net Configuration Assistant, and Oracle Net Manager.  

  !  Oracle Optimal Flexible Architecture (OFA)  A set of configuration guidelines created to ensure well-organized Oracle installations.  Oracle process A unit of execution that runs the Oracle database code. The process execution architecture depends on the operating system. Oracle processes include server processes and background processes.

  !  Oracle RAC  Oracle Real Application Clusters. Option that allows multiple concurrent database instances to share a single physical database.  

  ✗  Oracle Real Application Clusters  See Oracle RAC.  

  !  Oracle Sharding  A feature for OLTP applications that enables distribution and replication of data across a pool of Oracle databases in a shared-nothing architecture. Applications access the pool as a single, logical database called a sharded database (SDB).  Oracle Spatial and Graph A set of advanced features for spatial data and analysis and for physical, logical, network, and social and semantic graph applications. The spatial features provide a schema and functions that facilitate the storage, retrieval, update, and query of collections of spatial features in an Oracle database.  

  ✗  Oracle SQL  An implementation of the ANSI standard for SQL. Oracle SQL supports numerous features that extend beyond standard SQL.  

  ✗  Oracle Text (Text)  A full-text retrieval technology integrated with Oracle Database.  

  !  Oracle Virtual Private Database (VPD)  A security feature that enables you to create security policies to control database access at the row and column level. Essentially, VPD adds a dynamic WHERE clause to a SQL statement that is issued against the table, view, or synonym to which a VPD security policy was applied.  

  ✗  Oracle XA  An external interface that allows global transactions to be coordinated by a transaction manager other than Oracle Database.  

  ✗  Oracle XML DB  A set of Oracle Database technologies related to high-performance XML manipulation, storage, and retrieval. Oracle XML DB provides native XML support by encompassing both SQL and XML data models in an interoperable manner.  

  ✗  Oracle XML Developer's Kit (XDK)  A developer toolkit that contains the basic building blocks for reading, manipulating, transforming, and viewing XML documents, whether on a file system or in a database. APIs and tools are available for Java, C, and C++. The production Oracle XDK comes with a commercial redistribution license.  

  ✗  outer join  A join that returns all rows that satisfy the join condition and also returns some or all of those rows from one table for which no rows from the other satisfy the join condition.  

  ✗  parallel execution  The application of multiple CPU and I/O resources to the execution of a single database operation.  

  ✗  parse lock  A lock is held by a SQL statement or PL/SQL program unit for each schema object that it references. Parse locks are acquired so that the associated shared SQL area can be invalidated if a referenced object is altered or dropped.  

  ✗  partial index  An index that is correlated with the indexing properties of an associated partitioned table.  

  ✗  partition  A piece of a table or index that shares the same logical attributes as the other partitions. For example, all partitions in a table share the same column and constraint definitions. Each partition is an independent object with its own name and optionally its own storage characteristics.  

  ✗  partition elimination  The exclusion of partitions from a query plan. Whether the optimizer can eliminate partitions from consideration depends on the query predicate. A query that uses a local prefixed index always allows for index partition elimination, whereas a query that uses a local nonprefixed index might not.  

  ✗  partition key  A set of one or more columns that determines the partition in which each row in a partitioned table should go. Each row is unambiguously assigned to a single partition.  

  ✗  partitioned index  An index that is divided into smaller and more manageable pieces. Like partitioned tables, partitioned indexes improve manageability, availability, performance, and scalability.  

  ✗  partitioned table  A table that has one or more partitions, each of which is managed individually and can operate independently of the other partitions.  

  ✗  partitioning  The ability to decompose very large tables and indexes into smaller and more manageable pieces called partitions.  

  !  Patchin Oracle 

  ✗  PDB  In a multitenant container database (CDB), a portable collection of schemas, schema objects, and nonschema objects that appears to an Oracle Net client as a traditional Oracle database (non-CDB).  

  ✗  PDB administrator  A database administrator who manages one or more PDBs. A CDB administrator manages the whole CDB.  

  !  PDB/non-CDB compatibility guarantee  In the multitenant architecture, the guarantee that a PDB behaves the same as a non-CDB as seen from a client connecting with Oracle Net.  

  ✗  PDB restore point  Within a CDB, a restore point that usable only for a specific PDB. In contrast, a CDB restore point is usable by all PDBs.  

  ✗  performance profile  A specified share of system resources, CPU, parallel execution servers, and memory for a PDB or set of PDBs.  

  ✗  permanent tablespace  A tablespace that contains persistent schema objects. Every tablespace that is not a temporary tablespace is a permanent tablespace.  

  !  PGA  Program global area. A memory buffer that contains data and control information for a server process. See also SGA.

  ✗  physical backup  

  ✗  physical guess  The physical rowid of an index entry when it was first made. Oracle Database can use physical guesses to probe directly into the leaf block of any index-organized table, bypassing the primary key search.

  ✗  plan generator  The part of the optimizer that tries different access paths, join methods, and join orders for a given query block to find the plan with the lowest cost.  

  ✗  PL/SQL  Procedural Language/SQL. The Oracle Database procedural language extension to SQL. PL/SQL enables you to mix SQL statements with programmatic constructs such as procedures, functions, and packages.  

  ✗  PL/SQL anonymous block  A PL/SQL block that appears in an application, but is not named or stored in the database. In many applications, PL/SQL blocks may appear wherever SQL statements can appear.  

  ✗  PL/SQL collection  An ordered group of elements, all of the same type. Each element has a unique subscript that determines its position in the collection.  

  ✗  PL/SQL engine  The tool used to define, compile, and run PL/SQL program units. This engine is a special component of many Oracle products, including Oracle Database.  

  ✗  PL/SQL function  A schema object that consists of a set of SQL statements and other PL/SQL constructs, grouped together, stored in the database, and run as a unit to solve a specific problem or perform a set of related tasks, and that always returns a single value to the caller.  

  ✗  PL/SQL function result cache  A subset of the server result cache that stores function result sets.  

  ✗  PL/SQL package  A logical grouping of related PL/SQL types, variables, and subprograms.  

  ✗  PL/SQL procedure  A schema object that consists of a set of SQL statements and other PL/SQL constructs, grouped together, stored in the database, and run as a unit to solve a specific problem or perform a set of related tasks.  

  ✗  PL/SQL record  A composite variable that can store data values of different types, similar to a struct type in C, C++, or Java. Records are useful for holding data from table rows, or specific columns from table rows.  

  ✗  PL/SQL subprogram  A named PL/SQL block that can be invoked with a set of parameters 

  ✗  pluggable database (PDB)  See PDB.  

  ✗  point-in-time recovery  The incomplete recovery of database files to a noncurrent time.  See Also: media recovery, recover

  !  population  The transfer of data into the IM column store. Population does not insert new data into the database; rather, it brings existing data into memory and stores it in columnar format.  

  ✗  pragma  A directive that instructs the compiler to perform a compilation option. For example, the pragma AUTONOMOUS_TRANSACTION instructs the database that this procedure, when executed, is to be executed as a new autonomous transaction that is independent of its parent transaction.  

  ✗  precision  The total number of digits in a floating-point number. You specify a fixed-point number in the form NUMBER(p,s), where p represents the precision.  

  ✗  precompiler  A programming tool that enables you to embed SQL statements in a high-level source program written in a language such as C, C++, or COBOL.  

  ✗  predicate  The WHERE condition in a SQL statement.  

  ✗  prefix compression  The elimination of repeated occurrence of primary key column values in an index-organized table. Prefix compression was formerly known as key compression.  

  ✗  primary key  The column or set of columns that uniquely identifies a row in a table. Only one primary key can be defined for each table.  

  ✗  primary key constraint  An integrity constraint that disallows duplicate values and nulls in a column or set of columns.  

  ✗  private SQL area  An area in memory that holds a parsed statement and other information for processing. The private SQL area contains data such as bind variable values, query execution state information, and query execution work areas.  

  ✗  private temporary table  A memory-only temporary table whose data and metadata is session-private.  privilege The right to run a particular type of SQL statement, or the right to access an object that belongs to another user, run a PL/SQL package, and so on. The types of privileges are defined by Oracle Database.  

  ✗  privilege analysis  A security mechanism that captures privilege usage for a database according to a specified condition. For example, you can find the privileges that a user exercised during a specific database session.  

  ✗  procedural language  A language that describes how things should be done, not what should be done (as in declarative languages). C++ and Java are examples of procedural languages.  

  ✗  process  A mechanism in an operating system that can run a series of steps. By dividing the work of Oracle Database and database applications into several processes, multiple users and applications can connect to a single database instance simultaneously. See also background process; Oracle process; client process.

  ✗  process monitor (PMON)  The background process that detects the termination of other background processes. If a server or dispatcher process terminates abnormally, then the process monitor (PMON) group is responsible for performing process recovery.  

  ✗  process monitor (PMON) group  The group of background processes that is responsible for the monitoring and cleanup of other processes. The PMON group includes process monitor (PMON), Cleanup Main Process (CLMN), and Cleanup Helper Processes (CLnn).  program global area (PGA) See PGA.  

  ✗  program interface  The software layer between a database application and Oracle Database.  

  !  protected database  A client database whose backups are managed by a Recovery Appliance.  

  !  protection policy  A group of attributes that control how a Recovery Appliance stores and maintains backup data. Each protected database is assigned to exactly one protection policy, which controls all aspects of backup processing for that client.  

  ✗  pseudocolumn  A column that is not stored in a table, yet behaves like a table column.  

  ✗  query  An operation that retrieves data from tables or views. For example, SELECT * FROM employees is a query. See also implicit query and subquery.

  ✗  query block  A top-level SELECT statement, subquery or unmerged view.  

  ✗  query coordinator  In parallel execution, the user session or shadow process that coordinates the parallel execution servers. The parallel execution servers performs each operation in parallel if possible. When the parallel servers are finished executing the statement, the query coordinator performs any portion of the work that cannot be executed in parallel. Finally, the query coordinator returns any results to the user.  

  ✗  query optimization  The process of choosing the most efficient means of executing a SQL statement.  

  ✗  query plan  The execution plan used to execute a query.  

  ✗  query rewrite  An optimization technique that transforms a user request written in terms of master tables into a semantically equivalent request that includes materialized views.  

  ✗  query transformer  An optimizer component that decides whether it can rewrite the original SQL statement into a semantically equivalent SQL statement with a lower cost.  

  ✗  range partitioning  A type of partitioning in which the database maps rows to partitions based on ranges of values of the partitioning key. Range partitioning is the most common type of partitioning and is often used with dates.  

  ✗  RDMA  Remote Direct Memory Access. A communication protocol that enables a client to transfer data from the memory (DRAM) of the database server over the network without consuming server-side CPU.  read committed isolation level An isolation level that guarantees that a query executed by a transaction sees only data committed before the query—not the transaction—began.  

  ✗  read consistency  A consistent view of data seen by a user. For example, in statement-level read consistency the set of data seen by a SQL statement remains constant throughout statement execution. See also data concurrency; data consistency.

  ✗  read-only database  A database that is available for queries only and cannot be modified.  

  ✗  read-only database instance  A database instance that cannot process DML and does not support client connections.  

  ✗  read-only isolation level  An isolation level that is similar to the serializable isolation level, with one exception: read-only transactions do not permit data to be modified in the transaction unless the user is SYS.  

  ✗  read/write database instance  A database instance that can process DML and supports direct client connections. By default, a database instance is read/write.  

  !  real-time redo transport  The continuous transfer of redo changes from the SGA of a protected database to a Recovery Appliance. Real-time redo transport enables RMAN to provide a recovery point objective near 0. Typically, RMAN can recover to within a second of the time when the failure occurred. Protected databases write redo entries directly from the SGA to the Recovery Appliance as they are generated.  

  ✗  recoverable error  A class of errors that arise because of an external system failure, independently of the application session logic that is executing. Recoverable errors occur following planned and unplanned outages of networks, nodes, storage, and databases. An example of a nonrecoverable error is submission of invalid data values.  

  ✗  recoverer process (RECO)  In a distributed database, the background process that automatically resolves failures in distributed transactions.  

  !  Recovery Appliance  Shortened name for Zero Data Loss Recovery Appliance. Recovery Appliance is an Oracle Engineered System specifically designed to protect Oracle databases. Integrated with RMAN, it enables a centralized, incremental-forever backup strategy for hundreds to thousands of databases across the enterprise, using cloud-scale, fully fault-tolerant hardware and storage.  

  !  Recovery Appliance Backup Module  An Oracle-supplied SBT library that RMAN uses to send backups of protected databases over the network to the Recovery Appliance. The library must be installed in each Oracle home used by a protected database. The module functions as an SBT media management library that RMAN references when allocating or configuring a channel for backup to the Recovery Appliance. RMAN performs all backups to the Recovery Appliance, and all restores of complete backup sets, using this module.

  !  Recovery Appliance metadata database  The Oracle database that runs inside of the Recovery Appliance. This database stores configuration data such as user definitions, protection policy definitions, and client database definitions. The metadata database also stores backup metadata, including the contents of the delta store.  

  !  Recovery Appliance storage location  A set of Oracle ASM disk groups within Recovery Appliance that stores backups. A storage location can be shared among multiple protected databases. Every Recovery Appliance contains the default Recovery Appliance storage location named DELTA.  

  !  recovery catalog  A centralized backup repository located in an Oracle database. The recovery catalog contains metadata about RMAN backups.  

  !  Recovery Manager (RMAN)  See RMAN.  

  ✗  Recovery Manager (RMAN)  The primary utility for physical backup and recovery of Oracle databases. RMAN keeps records of Oracle databases in its own structure called an RMAN repository, manages storage of backups, validates backups. You can use it with or without the central information repository called a recovery catalog. If you do not use a recovery catalog, then RMAN uses the database's control file to store information necessary for backup and recovery operations. You can use RMAN with third-party media management software to back up files to tertiary storage.  See Also: backup piece, backup set, copy, media management software, recovery catalog

  !  recovery window goal  The time interval within which a protected database must be recoverable to satisfy business requirements. For each protected database in a protection policy, the Recovery Appliance attempts to ensure that the oldest backup on disk is able to support a point-in-time recovery to any time within the specified interval (for example, the past 7 days), counting backward from the current time.  

  ✗  recursive SQL  SQL that the database executes in the background to obtain space for database objects. You can think of recursive SQL as "side effect" SQL.  

  ✗  redo data 

  !  redo log  A set of files that protect altered database data in memory that has not been written to the data files. The redo log can consist of two parts: the online redo log and the archived redo log.  

  !  redo log buffer  Memory structure in the SGA that stores redo entries—a log of changes made to the database. The database writes the redo entries stored in the redo log buffers to an online redo log file, which the database uses when instance recovery is necessary.  

  !  redo record  A record in the online redo log that holds a group of change vectors, each of which describes a change made to a data block. Each redo log file consists of redo records.  

  !  redo thread  The redo generated by a database instance.  

  ✗  reference partitioning  A partitioning strategy in which a child table is solely defined through the foreign key relationship with a parent table. For every partition in the parent table, exactly one corresponding partition exists in the child table.  

  ✗  referenced key  In a foreign key relationship, the primary or unique key to which the foreign key refers. For example, in the common schema, the employees.department_id column is a foreign key, and the departments.department_id column is the referenced key.  

  ✗  referenced object  In a schema object dependency, the object that is referenced by another object's definition. For example, if the definition of object A references object B, then B is a referenced object for A.  

  ✗  referential integrity  A rule defined on a key in one table that guarantees that the values in that key match the values in a key in a related table (the referenced value).  

  ✗  relation  A set of tuples.  

  ✗  relational database  A database that conforms to the relational model, storing data in a set of simple relations.  

  ✗  relational database management system (RDBMS)  A management system that moves data into a relational database, stores the data, and retrieves it so that applications can manipulate it.  

  !  replay context  In Application Continuity, opaque information that the database returns to the client driver during normal application run time.  

  !  replication  The process of sharing database objects and data at multiple databases.  

  !  reserved pool  A memory area in the shared pool that Oracle Database can use to allocate large contiguous chunks of memory.  

  !  resource plan  A container for resource plan directives that specify how resources are allocated to resource consumer groups.  

  !  resource plan directive  A set of limits and controls for CPU, physical I/O, or logical I/O consumption for sessions in a consumer group.  

  !  restore point  A user-defined a name associated with an SCN of the database corresponding to the time of the creation of the restore point.  

  ✗  result set  The set of data retrieved from execution of a SELECT statement.  

  ✗  reverse key index  A type of B-tree index that physically reverses the bytes of each index key while keeping the column order. For example, if the index key is 20, and if the two bytes stored for this key in hexadecimal are C1,15 in a standard B-tree index, then a reverse key index stores the bytes as 15,C1.  

  ✗  right outer join  The result of a right outer join for table A and B contains all records of the right table B, even if the join condition does not match a record in the left table A. For example, if you perform a right outer join of employees (left) to departments (right), and if some departments contain no employees, then the query returns rows from departments with no matches in employees.  

  ✗  RMAN  Recovery Manager. An Oracle Database utility that backs up, restores, and recovers Oracle databases.  

  !  RMAN backup job  The set of BACKUP commands executed within a single RMAN session. For example, assume that you start the RMAN client, execute BACKUP DATABASE, BACKUP ARCHIVELOG, and RECOVER COPY, and then exit the RMAN client. The RMAN backup job consists of the database backup and the archived redo log backup.

  ✓  RMAN client  The executable $ORACLE_HOME/bin/rman

  !  RMAN client  An Oracle Database executable that interprets commands, directs server sessions to execute those commands, and records its activity in the target database control file. The RMAN executable is automatically installed with the database and is typically located in the same directory as the other database executables. For example, the RMAN client on Linux is named rman and is located in $ORACLE_HOME/bin.

  !  RMAN job  The set of RMAN commands executed in an RMAN session. For example, assume that you start the RMAN client, execute BACKUP DATABASE, BACKUP ARCHIVELOG, and RECOVER COPY, and then exit the RMAN client. The RMAN job consists of the two backups and the roll forward of the data file copy.

  !  RMAN maintenance commands  Commands that you can use to manage RMAN metadata records and backups. The maintenance commands are CATALOG, CHANGE, CROSSCHECK, and DELETE.

  ✓  RMAN parameters 

  !  RMAN repository  The record of RMAN metadata about backup and recovery operations on the target database.

  !  RMAN session  An RMAN session begins when the RMAN client is started and ends when you exit from the client or the RMAN process is terminated. Multiple RMAN commands can be executed in a single RMAN session.

  ✗  role  A set of privileges that can be granted to database users or to other roles.  

  ✗  row  A set of column information corresponding to a single record in a table. The database stores rows in data blocks.  

  ✗  row chaining  A situation in which Oracle Database must store a row in a series or chain of blocks because it is too large to fit into a single block.  

  ✗  row lock  A lock on a single row of table. A transaction acquires a row lock for each row modified by an INSERT, UPDATE, DELETE, MERGE, or SELECT ... FOR UPDATE statement.  

  ✗  row major format  A type of table storage in which all columns of one row are stored together, followed by all columns of the next row, and so on.  

  ✗  row migration  A situation in which Oracle Database moves a row from one data block to another data block because the row grows too large to fit in the original block.  

  ✗  row piece  A row is stored in a variable-length record. This record is divided into one or more row pieces. Each row piece has a row header and column data.  

  ✗  row set  A set of rows returned by a step in an execution plan.  

  ✗  row source  An iterative control structure that processes a set of rows and produces a row set.  

  ✗  row source generator  Software that receives the optimal plan from the optimizer and outputs the execution plan for the SQL statement.  

  ✗  row trigger  A trigger that fires each time the table is affected by the triggering statement. For example, if a statement updates multiple rows, then a row trigger fires once for each row affected by the UPDATE.  

  ✗  rowid  A globally unique address for a row in a database.  

  ✗  sample schemas  A set of interlinked schemas that enable Oracle documentation and Oracle instructional materials to illustrate common database tasks.  

  ✗  savepoint  A named SCN in a transaction to which the transaction can be rolled back.  

  ✗  SBT  System Backup to Tape. This term specifies a nondisk backup device type, typically a tape library or tape drive. RMAN supports channel of type disk and SBT.

  ✗  scale  In a floating-point number, the number of digits from the decimal point to the least significant digit. You specify a fixed-point number in the form NUMBER(p,s), where s represents the scale.  

  ✗  schema  A named collection of database objects, including logical structures such as tables and indexes. A schema has the name of the database user who owns it.  

  ✗  schema object  A logical structure of data stored in a schema. Examples of schema objects are tables, indexes, sequences, and database links.  

  ✗  schema object dependency  The referencing of one object by another object. For example, a view contains a query that references tables or views, or a PL/SQL subprogram invokes other subprograms.  

  !  SCN  System Change Number. A database ordering primitive. The value of an SCN is the logical point in time at which changes are made to a database.  

  ✗  secondary index  An index on an index-organized table. In a sense, it is an index on an index.  

  ✗  SecureFiles LOB storage  SecureFiles LOB storage is the default storage mechanism for LOBs. The SECUREFILE LOB parameter enables advanced features, including compression and deduplication (part of the Advanced Compression Option) and encryption (part of the Advanced Security Option).  

  ✗  security policy  A set of methods for protecting a database from accidental or malicious destruction of data or damage to the database infrastructure.  

  ✗  segment  A set of extents allocated for a specific database object such as a table, index, or table cluster.

  ✗  select list  In a SELECT statement, the list of expressions that appears after the SELECT keyword and before the FROM clause.  

  ✗  selectivity  A value indicating the proportion of a row set retrieved by a predicate or combination of predicates, for example, WHERE last_name = 'Smith'. A selectivity of 0 means that no rows pass the predicate test, whereas a value of 1 means that all rows pass the test. The adjective selective means roughly "choosy." Thus, a highly selective query returns a low proportion of rows (selectivity close to 0), whereas an unselective query returns a high proportion of rows (selectivity close to 1).

  ✗  self join  A join of a table to itself.  

  ✗  self-referential integrity constraint  A constraint in which a foreign key references a parent key in the same table. For example, a constraint could ensure that every value in the employees.manager_id column corresponds to an existing value in the employees.employee_id column.  

  ✗  sequence  A schema object that generates a serial list of unique numbers for table columns.  

  ✗  serial execution  A single server process performs all necessary processing for the sequential execution of a SQL statement.  

  ✗  serializability  A transaction isolation model that enables a transaction to operate in an environment that makes it appear as if no other users were modifying data in the database.  

  ✗  serializable isolation level  A level of isolation that guarantees that a transaction sees only changes committed at the time the transaction—not the query—began and changes made by the transaction itself.  

  !  server  In a client/server architecture, the computer that runs Oracle software and handles the functions required for concurrent, shared data access. The server receives and processes the SQL and PL/SQL statements that originate from client applications.  

  !  server parameter file file  A server-side binary file containing initialization parameter settings that is read and written to by the database.  

  ✗  server process  An Oracle process that communicates with a client process and Oracle Database to fulfill user requests. The server processes are associated with a database instance, but are not part of the instance.  

  !  server result cache  A memory pool within the shared pool. This memory pool consists of the SQL query result cache—which stores results of SQL queries—and the PL/SQL function result cache, which stores values returned by PL/SQL functions.  

  ✗  service handler  In Oracle Net, a dedicated server process or dispatcher that acts as a connection point to a database.  

  ✗  service name  In Oracle Net, the logical representation of a service used for client connections.  

  ✗  service registration  In Oracle Net, a feature by which the listener registration process (LREG) dynamically registers instance information with a listener, which enables the listener to forward client connection requests to the appropriate service handler.  

  ✗  service-oriented architecture (SOA)  A multitier architecture relying on services that support computer-to-computer interaction over a network.  

  ✗  session  A logical entity in the database instance memory that represents the state of a current user login to a database. A single connection can have 0, 1, or more sessions established on it.  

  !  SGA  System global area. A group of shared memory structures that contain data and control information for one Oracle database instance.  

  ✗  shadow extent  An extent in a shadow tablespace. A one-to-one mapping exists between a shadow extent and a tracked data file.  shadow lost write protection A data protection feature that uses a shadow tablespace to detect a lost write automatically in any tracked data file.  shadow tablespace A tablespace enabled for shadow lost write protection. The tablespace tracks the SCNs and other metadata for data block stored in a tracked data file. A single shadow tablespace may contain descriptive data for many regular data files.  shard A single database participating in a sharding configuration.  

  ✗  shard director  A GDS infrastructure component that uses the global service manager to provide direct routing of requests from the application tier to an individual shard.  sharded database (SDB) In a sharding architecture, collection of shards that appear to applications as a single logical database.  sharded table A table that is split horizontally across a sharded database (SDB), so that each shard contains the table with the same columns but a different subset of rows.  sharding A data tier architecture in which data is horizontally partitioned across independent databases. Sharding is a shared-nothing database architecture because shards do not share physical resources such as CPU, memory, or storage devices. Shards are also loosely coupled in terms of software; they do not run clusterware.  sharding key A partitioning key for a sharded table.  share lock A lock that permits the associated resource to be shared by multiple transactions, depending on the operations involved. Multiple transactions can acquire share locks on the same resource.  

  !  shared pool  Portion of the SGA that contains shared memory constructs such as shared SQL areas.  

  ✗  shared server  A database configuration that enables multiple client processes to share a small number of server processes.  

  ✗  See also dedicated server.  

  !  shared SQL area  An area in the shared pool that contains the parse tree and execution plan for an SQL statement. Only one shared SQL area exists for a unique statement.  

  ✗  shared temporary tablespace  A temporary tablespace that resides on shared storage and is accessible by all database instances. Starting in Oracle Database 12c Release 2 (12.2), temporary tablespaces are either shared or local. In previous releases, all temporary tablespaces were shared temporary tablespaces.  shared undo mode The use of a single set of undo data files for an entire CDB.  simple database operation A single SQL statement, or a single PL/SQL procedure or function.  

  ✗  simple trigger  A trigger on a table that enables you to specify actions for exactly one timing point. For example, the trigger might fire before the firing statement.  

  ✗  single-level partitioning  A partitioning strategy that uses only one method of data distribution, for example, only list partitioning or only range partitioning.  

  ✗  site failure  An event that causes all or a significant portion of an application to stop processing or slow to an unusable service level.  

  ✗  smallfile tablespace  A tablespace that can contain multiple data files or temp files, but the files cannot be as large as in a bigfile tablespace.  

  ✗  soft parse  The reuse of existing code when the parsed representation of a submitted SQL statement exists in the shared pool and can be shared. See also hard parse.

  ✗  software code area  A portion of memory that stores code that is being run or can be run.  

  ✗  sorted hash cluster  A hash cluster that stores the rows corresponding to each value of the hash function in such a way that the database can efficiently return them in sorted order. The database performs the optimized sort internally.  

  ✗  SQL  Structured Query Language. A nonprocedural language to access a relational database. Users describe in SQL what they want done, and the SQL language compiler automatically generates a procedure to navigate the database and perform the task. Oracle SQL includes many extensions to the ANSI/ISO standard SQL language. See also SQL*Plus; PL/SQL.

  ✗  SQL Developer  A graphical version of SQL*Plus, written in Java, that supports development in SQL and PL/SQL.  

  ✗  SQL parsing  This stage of SQL processing that involves separating the pieces of a SQL statement into a data structure that can be processed by other routines.  

  ✗  SQL plan baseline  In SQL plan management, a set of one or more accepted plans for a repeatable SQL statement. The effect of a SQL plan baseline is that the optimizer limits its choice to a verified plan in the baseline.  

  ✗  SQL plan management  A preventative mechanism that enables the optimizer to automatically manage execution plans, ensuring that the database uses only verified plans.  

  ✗  SQL profile  A set of auxiliary information built during automatic tuning of a SQL statement. A SQL profile is to a SQL statement what statistics are to a table. The optimizer can use SQL profiles to improve cardinality and selectivity estimates, which in turn leads the optimizer to select better plans.  

  ✗  SQL query result cache  A subset of the server result cache that stores the results of queries and query fragments.  

  ✗  SQLJ  An ANSI standard for embedding SQL statements in Java programs. You can combine SQLJ programs with JDBC.  

  ✗  SQL*Plus  Oracle tool used to run SQL statements against Oracle Database.  

  !  standby database  An independent copy of a production database that you can use for disaster protection in a high availability environment.  

  ✓  standby redo log 

  !  star schema  A relational schema whose design represents a dimensional data model. The star schema consists of one or more fact tables and one or more dimension tables that are related through foreign keys. See also dimension table; fact table.

  !  state object  A session-level structure that contains metadata about the status of database resources such as processes, sessions, and transactions in the SGA.

  ✗  statement trigger  A trigger that is fired once on behalf of the triggering statement, regardless of the number of rows affected by the triggering statement.  

  ✗  statement-level atomicity  The characteristic of a SQL statement as an atomic unit of work that either completely succeeds or completely fails.  

  ✗  statement-level read consistency  The guarantee that data returned by a single query is committed and consistent for a single point in time.  

  ✗  statement-level rollback  A database operation in which the effects of an unsuccessful SQL statement are rolled back because the statement caused an error during execution.  

  ✗  stored procedure  A named PL/SQL block or Java program that Oracle Database stores in the database. Applications can call stored procedures by name.  

  !  Streams pool  A memory pool that stores buffered queue messages.  

  ✗  Structured Query Language (SQL)  See SQL.  

  ✗  subquery  A query nested within another SQL statement. Unlike implicit queries, subqueries use a SELECT statement to retrieve data.  

  ✗  summary  In a data warehouse, an aggregate view that reduces query time by precalculating joins and aggregation operations and storing the results in a table.  

  ✗  surrogate key  A system-generated incrementing identifier that ensures uniqueness within a table. Typically, a sequence generates surrogate keys.  

  ✗  synonym  An alias for a schema object. You can use synonyms to provide data independence and location transparency.  

  !  system change number (SCN)  See SCN.  

  !  system container  The container that includes the CDB root and all PDBs in the CDB.  system event trigger An event trigger caused by events such as error messages, or database instance startup and shutdown.  

  ✗  system global area (SGA)  See SGA.  

  ✗  system monitor process (SMON)  The background process in charge of a variety of system-level cleanup duties, including instance recovery, recovering terminated transactions that were skipped during instance recovery, Cleaning up unused temporary segments, and Coalescing contiguous free extents within dictionary-managed tablespaces.  

  ✗  table  Basic unit of data storage in Oracle Database. Data in tables is stored in rows and columns.  

  ✗  table cluster  A schema object that contains data from one or more tables, all of which have one or more columns in common. In table clusters, the database stores together all the rows from all tables that share the same cluster key.  

  ✗  table compression  The compression of data segments to reduce disk space in a heap-organized table or table partition.  

  ✗  table function  A user-defined PL/SQL function that returns a collection of rows (a nested table or varray). You can select from this collection as if it were a database table by invoking the table function inside the TABLE clause in a SELECT statement.  

  ✗  table lock  A lock on a table that is acquired by a transaction when a table is modified by an INSERT, UPDATE, DELETE, MERGE, SELECT ... FOR UPDATE, or LOCK TABLE statement.  

  ✗  tablespace  A database storage unit that groups related logical structures together. The database data files are stored in tablespaces.  

  ✗  tablespace set  In Oracle Sharding, tablespaces that are distributed across a sharded database (SDB) and managed as a unit.  temp file A file that belongs to a temporary tablespace. The temp files in temporary tablespaces cannot contain permanent database objects.  

  ✗  temporary segment  A segment created by Oracle Database when a SQL statement needs a temporary database area to complete execution.  

  ✗  temporary table  A table that holds an intermediate result set for the duration of a transaction or a session. Only the current session can see the data in temporary tables.  

  ✗  temporary tablespace  A tablespace that can only contain transient data that persists only for the duration of a session. No permanent schema objects can reside in a temporary tablespace. Every temporary tablespace is either a shared temporary tablespace or a local temporary tablespace. Unless otherwise stated, the term temporary tablespace means shared temporary tablespace.

  ✗  temporary undo segment  An optional space management container for temporary undo data only.  

     TFA  Trace file analyzer

  !  trace file  An administrative file that contain diagnostic data used to investigate problems. Oracle Database writes trace files to ADR.  

  !  tracked data file  A data file whose block SCNs are tracked by a shadow tablespace, enabling shadow lost write protection.  transaction Logical unit of work that contains one or more SQL statements. All statements in a transaction commit or roll back together. The use of transactions is one of the most important ways that a database management system differs from a file system.  

  !  transaction entry  Space in the block header that is required for every transaction that updates the block. In data blocks allocated to segments that support transactional changes, free space can also hold transaction entries when the header space is depleted.  

  !  Transaction Guard  A database feature that uses a logical transaction ID to prevent the possibility of a client application submitting duplicate transactions after a recoverable error.  

  ✗  transaction idempotence  The ability to return a guaranteed outcome for a transaction: whether it committed and whether the call was completed.  

  !  transaction ID  An identifier is unique to a transaction and represents the undo segment number, slot, and sequence number.  

  ✗  transaction-level read consistency  The guarantee of read consistency to all queries in a transaction. Each statement in a transaction sees data from the same point in time, which is the time at which the transaction began.  

  ✗  transaction name  An optional, user-specified tag that serves as a reminder of the work that the transaction is performing. Name a transaction with the SET TRANSACTION ... NAME statement.  

  !  transaction recovery  A phase of instance recovery in which uncommitted transactions are rolled back.  

  !  transaction table  The data structure within an undo segment that holds the transaction identifiers of the transactions using the undo segment.

  ✗  transition point  The high value of the range partitions determined by the range partition key value.  

  ✗  Transparent Data Encryption  A database feature that encrypts individual table columns or a tablespace. When a user inserts data into an encrypted column, the database automatically encrypts the data. When users select the column, the data is decrypted. This form of encryption is transparent, provides high performance, and is easy to implement.  

  ✗  transportable tablespace  A tablespace that you can copy or move between databases. Oracle Data Pump provides the infrastructure for transportable tablespaces.  

  ✗  trigger  A PL/SQL or Java procedure that fires when a table or view is modified or when specific user or database actions occur. Procedures are explicitly run, whereas triggers are implicitly run.  

  ✗  tuple  An unordered set of attribute values.  

  ✗  two-phase commit mechanism  A mechanism in a distributed database that guarantees that all databases participating in a distributed transaction either all commit or all undo the statements in the transaction.  

  !  UGA  User global area. Session memory that stores session variables, such as logon information, and can also contain the OLAP pool.  

  !  undo data  Records of the actions of transactions, primarily before they are committed. The database can use undo data to logically reverse the effect of SQL statements. Undo data is stored in undo segments.  

  !  undo retention period  The minimum amount of time that the database attempts to retain old undo data before overwriting it.  

  !  undo retention period  The minimum amount of time that Oracle Database attempts to retain old undo data in the undo tablespace before overwriting it. Old (committed) undo data that is older than the current undo retention period is said to be expired. Old undo data with an age that is less than the current undo retention period is said to be unexpired.

  !  undo segment  A segment in an undo tablespace.  

  !  undo tablespace  A tablespace containing undo tablespace when automatic undo management mode is enabled.  

  !  undo tablespace  A dedicated tablespace that stores only undo information when the database is run in automatic undo management mode.

  ✗  Unicode  A universal encoded character set that can store information in any language using a single character set.  

  !  unified audit policy  A policy that you can use to configure auditing on SQL statements, system privileges, schema objects, roles, administrative and non-administrative users, application context values, and policy creations for various applications and events.  

  !  unified audit trail  An audit trail provides unified storage for audit records from all types of auditing.  

  ✗  unique key  A single column with a unique key constraint.  

  ✗  unique key constraint  An integrity constraint that requires that every value in a column or set of columns be unique.  

  !  universal rowid  A data type that can store all types of rowids. Oracle uses universal rowids to store the addresses of index-organized and non-Oracle tables.  

  ✗  unusable index  An index that is not maintained by DML operations and which the optimizer ignores. All indexes are usable (default) or unusable.  

  ✗  updatable join view  A view that is defined on two or more base tables or views and permits DML operations.  

  ✗  user event trigger  An event trigger that is fired because of events related to user logon and logoff, DDL statements, and DML statements.  

  !  user global area (UGA)  See UGA.  

  ✗  user name  The name by which a user is known to Oracle Database and to other users. Every user name is associated with a password, and both must be entered to connect to Oracle Database.  

  ✗  user privilege  The right to run specific SQL statements.  

  ✗  user process  See client process.  

  ✗  user profile  A named set of resource limits and password parameters that restrict database usage and database instance resources for a user.  

  ✗  view  A custom-tailored presentation of the data in one or more tables. The views do not actually contain or store data, but derive it from the tables on which they are based.  

  ✗  virtual column  A column that is not stored on disk. The database derives the values in virtual columns on demand by computing a set of expressions or functions.  

  ✗  virtual full backup  A complete database image as of one distinct point in time, maintained efficiently by a Recovery Appliance through the indexing of incremental backups from a protected database. The virtual full backups contain individual blocks from multiple incremental backups. For example, if you take a level 0 backup on Monday with SCN 10000, and if you take an incremental level 1 backup on Tuesday with SCN 11000, then the Recovery Appliance metadata database shows a virtual level 0 backup current to SCN 11000.  

  ✗  warehouse compression  Hybrid Columnar Compression specified with COLUMN STORE COMPRESS FOR QUERY. This type of compression is useful in data warehouses.

  ✗  whole database backup  A backup of the control file and all data files that belong to a database.

  !  work area  A private allocation of PGA memory used for memory-intensive operations.  

  !  write-ahead protocol  The protocol that mandates that before the database writer process can write a dirty buffer, the database must write to disk the redo records associated with changes to the buffer.  

  !  zone  Within a zone map, a zone is a set of contiguous data blocks that stores the minimum and maximum values of relevant columns.  

  !  zone map  Within an attribute-clustered table, a zone map is an independent access structure that divides data blocks into zones.  

Backup recovery

✗	active database duplication	A duplicate database that is created over a network without restoring backups of the target database. This technique is an alternative to backup-based duplication.
✗	ancestor incarnation	The parent incarnation is the database incarnation from which the current incarnation branched following an OPEN RESETLOGS operation. The parent of the parent incarnation is an ancestor incarnation. Any parent of an ancestor incarnation is also an ancestor incarnation. application container A named set of application PDBs that are plugged in to an application root. application PDB A PDB that is plugged in to an application container. application root The root container within an application container. Every application container has exactly one application root. An application root can contain common objects and is created with the CREATE PLUGGABLE DATABASE statement.
✗	archival backup	A database backup that is exempted from the normal backup and recovery strategy. Typically, these backups are archived onto separate storage media and retained for long periods.
✗	archived redo log	A copy of a filled member of an online redo log group made when the database is in ARCHIVELOG mode. After the LGWR process fills each online redo log with redo records, the archiver process copies the log to one or more redo log archiving destinations. This copy is the archived redo log. RMAN does not distinguish between an original archived redo log and an image copy of an archived redo log; both are considered image copies.
✗	archived redo log deletion policy	A configurable, persistent RMAN policy that governs when archived redo logs can be deleted. You can configure the policy with the CONFIGURE ARCHIVELOG DELETION POLICY command.
✗	archived redo log failover	An RMAN feature that enables RMAN to complete a backup even when some archived log destinations are missing logs or have logs with corrupt blocks. For example, if you back up logs in the fast recovery area that RMAN determines are corrupt, RMAN can search for logs in other archiving locations and back them up instead if they are intact.
✗	ARCHIVELOG mode	The mode of the database in which Oracle Database copies filled online redo logs to disk. Specify the mode at database creation or with the ALTER DATABASE ARCHIVELOG statement. See Also: archived redo log, NOARCHIVELOG mode
✗	archiving	The operation in which a filled online redo log file is copied to an offline log archiving destination. An offline copy of an online redo logs is called an archived redo log. You must run the database in ARCHIVELOG mode to archive redo logs.
✗	asynchronous I/O	A server process can begin an I/O and then perform other work while waiting for the I/O to complete while RMAN is either reading or writing data. RMAN can also begin multiple I/O operations before waiting for the first I/O to complete.
✗	automatic channel allocation	The ability of RMAN to perform backup and restore tasks without requiring the use of the ALLOCATE CHANNNEL command. You can use the CONFIGURE command to specify disk and tape channels. Then, you can issue commands such as BACKUP and RESTORE at the RMAN command prompt without manually allocating channels. RMAN uses whatever configured channels that it needs to execute the commands.
✗	Automatic Storage Management (ASM)	A vertical integration of both the file system and the volume manager built specifically for Oracle Database files. ASM consolidates storage devices into easily managed disk groups and provides benefits such as mirroring and striping without requiring a third-party logical volume manager.
✗	automatic undo management mode	A mode of the database in which undo data is stored in a dedicated undo tablespace. The only undo management that you must perform is the creation of the undo tablespace. All other undo management is performed automatically.
✗	auxiliary channel	An RMAN auxiliary channel that is connected to an auxiliary instance. An auxiliary channel is specified with the AUXILIARY keyword of the ALLOCATE CHANNEL or CONFIGURE CHANNEL command.
✗	auxiliary database	(1) A database created from target database backups with the RMAN DUPLICATE command. (2) A temporary database that is restored to a new location and then started with a new instance name during tablespace point-in-time recovery (TSPITR). A TSPITR auxiliary database contains the recovery set and auxiliary set.
✗	auxiliary destination	In a transportable tablespace operation, the location on disk where auxiliary set files such as the parameter file, data files (other than those of the tablespaces being transported), control files, and online redo logs of the auxiliary instance can be stored.
✗	auxiliary instance	The Oracle instance associated with an auxiliary database, or the temporary instance used in tablespace point-in-time recovery (TSPITR) or a transportable tablespace operation.
✗	auxiliary set	In TSPITR, the set of files that is not in the recovery set but which must be restored in the auxiliary database for the TSPITR operation to be successful. In a transportable tablespace operation, the auxiliary set includes data files and other files required for the tablespace transport but which are not themselves part of the recovery set.
✗	backup	(1) A backup copy of data, that is, a database, tablespace, table, data file, control file, or archived redo log. Backups can be physical (at the database file level) or logical (at the database object level). Physical backups can be created by using RMAN to back up one or more data files, control files or archived redo log files. You can create logical backups with Data Pump Export. (2) In an RMAN context, the output of the BACKUP command. The output format of a backup can be a backup set, proxy copy, or image copy. Logs archived by the database are considered copies rather than backups.
✗	backup and recovery	The set of concepts, procedures, and strategies involved in protecting the database against data loss due to media failure or users errors.
✗	backup-based duplication	A duplicate database that is created by restoring and recovering backups of the target database. This technique is an alternative to active database duplication.
✗	backup control file	A backup of the control file. You can back up the control file with the RMAN backup command or with the SQL statement ALTER DATABASE BACKUP CONTROLFILE TO 'filename'.
✗	backup encryption	The encryption of backup set by using an algorithm listed in V$RMAN_ENCRYPTION_ALGORITHMS. RMAN can transparently encrypt data written to backup sets and decrypt those backup sets when they are needed in a RESTORE operation. RMAN offers three modes of encryption: transparent, password protected, and dual mode.
✗	backup mode	The database mode (also called hot backup mode) initiated when you issue the ALTER TABLESPACE ... BEGIN BACKUP or ALTER DATABASE BEGIN BACKUP command before taking an online backup. You take a tablespace out of backup mode when you issue the ALTER TABLESPACE ... END BACKUP or ALTER DATABASE END BACKUP command. When making a user-managed backup of data files in an online tablespace, you must place the tablespace in backup mode to protect against the possibility of a fractured block. In backup mode, updates to the database create more than the usual amount of redo. Each time a block in the buffer cache becomes dirty, the database must write an image of the changed block to the redo log file, in addition to recording the changes to the data. RMAN does not require you to put the database in backup mode. See Also: corrupt block
✗	backup optimization	A configuration enabling RMAN to automatically skip backups of files that it has already backed up. You enable and disable backup optimization with the CONFIGURE command.
✗	backup retention policy	A (user-defined) policy that determines how long backups and archived logs must be retained for media recovery.
✗	backup undo optimization	The exclusion of undo not needed for recovery of an RMAN backup because the it describes and contains already-committed transactions. For example, a user updates the salaries table in the USERS tablespace. The change is written to the USERS tablespace, while the before image of the data is written to the undo tablespace. A subsequent RMAN backup of the undo tablespace may not include the undo for the salary change. Backup undo optimization is built-in RMAN behavior and cannot be disabled.
✗	backup window	A period of time during which a backup activity must complete.
✗	base recovery catalog	The entirety of the recovery catalog schema. The base recovery catalog is distinguished from a virtual private catalog, which is a subset of a recovery catalog.
✓	binary compression	RMAN can create backup sets in a compressed format.
✗	block change tracking	A database option that causes Oracle Database to track data file blocks affected by each database update. The tracking information is stored in a block change tracking file. When block change tracking is enabled, RMAN uses the record of changed blocks from the change tracking file to improve incremental backup performance by only reading those blocks known to have changed, instead of reading data files in their entirety.
✗	block change tracking file	A binary file used by RMAN to record changed blocks to improve incremental backup performance. You create and rename this file with the ALTER DATABASE statement.
✗	block media recovery	The recovery of specified blocks within a data file with the Recovery Manager RECOVER ... BLOCK command. Block media recovery leaves the affected data files online and restores and recovers only the damaged or corrupted blocks.
✗	breaking a mirror	The termination of a disk mirroring procedure so that a mirror image is no longer kept up-do-date.
✗	CDB	An Oracle Database installation that contains at least one PDB. A CDB also contains one root and one seed. Every Oracle Database is either a CDB or a non-CDB.
✗	CDB restore point	An alias for an SCN or a point in time in a multitenant container database (CDB). CDB restore points are accessible to all PDBs within the CDB.
✗	auxiliary channel	An RMAN channel represents one stream of data to or from a backup device. A channel can either be a DISK channel (used to perform disk I/O) or an SBT channel (used to perform I/O through a third-party media management software). Each allocated channel starts a new Oracle Database session. The session then performs backup, restore, and recovery operations. See Also: target database
✗	channel parallelism	Allocating multiple channels for RMAN operations.
✗	checksum	A number calculated by the database from all the bytes stored in a data or redo block. If the DB_BLOCK_CHECKSUM initialization parameter is enabled, then the database calculates the checksum for every data file or online redo log block and stores it in the block header when writing to disk. The database can use the checksum value to check consistency. circular reuse records Control file records containing information used by RMAN for backups and recovery operations. These records are arranged in a logical ring. When all available record slots are full, Oracle either expands the control file to make room for a new records or overwrites the oldest record. The CONTROL_FILE_RECORD_KEEP_TIME initialization parameter controls how many days records must be kept before they can be overwritten. The default for CONTROL_FILE_RECORD_KEEP_TIME is 7 days. See Also: noncircular reuse records
✗	closed backup	A backup of one or more database files taken while the database is closed. Typically, closed backups are whole database backups. If you closed the database consistently, then all the files in the backup are consistent. Otherwise, the backups are inconsistent. See Also: consistent shutdown, consistent backup
✗	cold backup	See closed backup
✗	common user	In a multitenant container database (CDB), a database user that exists with the same identity in the root and in every existing and future PDB.
✗	consistent shutdown	A database shut down with the IMMEDIATE, TRASACTIONAL, or NORMAL options of the statement. A database shut down cleanly does not require recovery; it is already in a consistent state.
✗	control file autobackup	The automatic backup of the current control file and server parameter file file that RMAN makes after backups and, if the database is in ARCHIVELOG mode, after structural changes. The control file autobackup has a default file name that allows RMAN to restore it even if the control file and recovery catalog are lost. You can override the default file name.
✗	convert script	A script generated by the CONVERT DATABASE command that you can use to convert data file formats on the destination host.
✗	copy	To back up a bit-for-bit image of an Oracle file (Oracle data files, control files, and archived redo logs) onto disk. You can copy in two ways: Using operating system utilities (for example, the UNIX cp or dd) Using the RMAN BACKUP AS COPY command See Also: backup
✗	corrupt block	An Oracle block that is not in a recognized Oracle format, or whose contents are not internally consistent. Typically, corruptions are caused by faulty hardware or operating system problems. Oracle identifies corrupt blocks as either logically corrupt (an Oracle internal error) or media corrupt (the block format is not correct). You can repair a media corrupt block with block media recovery, or dropping the database object that contains the corrupt block so that its blocks are reused for another object. If media corruption is due to faulty hardware, then neither solution works until the hardware fault is corrected.
✗	crash recovery	The automatic application of online redo records to a database after either a single-instance database crashes or all instances of an Oracle Real Applications Cluster configuration crash. Crash recovery only requires redo from the online logs; archived redo logs are not required. See Also: recover
✗	cross-platform backup	A backup that is created on the source database and can be restored on the destination database that is running on a different platform than the source platform. Cross-platform backups are used to transport data across platforms. Cross-platform operations can be performed either on the source database or destination database. However, they are often performed on the destination database because this is the usually the non-production database.
✗	crosscheck	A check to determine whether files on disk or in the media management catalog correspond to the data in the RMAN repository. Because the media management software can mark tapes as expired or unusable, and because files can be deleted from disk or otherwise become corrupted, the RMAN repository can contain outdated information about backups. Run the CROSSCHECK command to perform a crosscheck. See Also: validation
✗	cumulative incremental backup	An incremental backup that backs up all the blocks changed since the most recent backup at level 0. When recovering with cumulative incremental backups, only the most recent cumulative incremental backup must be applied. See Also: differential incremental backup, incremental backup
✗	current incarnation	The database incarnation in which the database is currently generating redo.
✗	data integrity check	An invocation of a checker, which is a diagnostic procedure registered with the Health Monitor.
✗	data repair	The use of media recovery or Oracle Flashback Technology to recover lost or corrupted data.
✗	database area	A location for the Oracle managed data files, control files, and online redo log files. The database area is specified by the DB_CREATE_FILE_DEST initialization parameter.
✗	database checkpoint	The thread checkpoint that has the lowest SCN. All changes in all enabled redo threads with SCNs before the database checkpoint SCN are guaranteed to have been written to disk. See Also: checkpoint, data file checkpoint
✗	database identifier	See DBID
✗	database registration	See registration
✗	data file checkpoint	The SCN so that every transaction with a smaller SCN is guaranteed to be stored in the data file.
✗	data file media recovery	The application of redo records to a restored data file to roll it forward to a more current time. Unless you are doing block media recovery, the data file must be offline while being recovered.
✗	DBID	An internal, uniquely generated number that differentiates databases. Oracle creates this number automatically when you create the database.
✗	destination database	The database into which data from the source database is being transported.
✗	destination host	The computer on which a duplicate database resides.
✗	destination platform	When transporting data across platforms, the platform on which the destination database is running.
✗	differential incremental backup	A type of incremental backup that backs up all blocks that have changed since the most recent backup at level 1 or level 0. For example, in a differential level 1 backup RMAN determines which level 1 or level 0 incremental backup is most recent and then backs up all blocks changed since that backup. Differential backups are the default type of incremental backup. When recovering using differential incremental backups, RMAN must apply all differential incremental level 1 backups since the restored data file backup. See Also: cumulative incremental backup, incremental backup
✗	direct ancestral path	When multiple OPEN RESETLOGS operations have been performed, the incarnation path that includes the parent incarnation of the current database incarnation and each ancestor incarnation of the current incarnation.
✗	disaster recovery	A strategic response to the loss of all data associated with a database installation. For example, a fire may destroy a server in a data center, forcing you to reinstall Oracle Database on a new server and recover the lost database from backups.
✗	disk controller	A hardware component that is responsible for controlling one or more disk drives.
✗	disk group	A collection of disks that are managed as a unit by Automatic Storage Management (ASM). The components of a disk group include disks, files, and allocation units.
✗	disk quota	A user-specified limit to the size of the fast recovery area area.
✗	duplexed backup set	In RMAN, a duplexed backup set is an RMAN-generated identical copy of a backup set. Each backup piece is in the original backup set is copied, with each copy getting a unique copy number (for example, 0tcm8u2s_1_1 and 0tcm8u2s_1_2).
✗	duplicate database	A database created from target database backups using the RMAN duplicate command. See Also: auxiliary database
✗	expired backup	A backup whose status in the RMAN repository is EXPIRED, which means that the backup was not found. RMAN marks backups and copies as expired when you run a CROSSCHECK command and the files are absent or inaccessible.
✗	export	The extraction of logical data (that is, not physical files) from a database into a binary file using Data Pump Export. You can then use Data Pump Import to import the data into a database. See Also: logical backup
✗	export dump file	A file created by the Data Pump Export utility. The dump file set is made up of one or more disk files that contain table data, database object metadata, and control information. The files are written in a proprietary, binary format.
✗	failure	For Data Recovery Advisor, a failure is a persistent data corruption that has been diagnosed by the database. A failure can manifest itself as observable symptoms such as error messages and alerts, but a failure is different from a symptom because it represents a diagnosed problem. Failures are recorded in a repository for diagnostic data located outside of the database. For each failure, Data Recovery Advisor generates a problem statement that unambiguously describes it. Examples of failures include inaccessible data files and corrupted undo tablespace. Data Recovery Advisor maps every failure to a repair option or set of repair options.
✗	failure priority	The priority of a failure diagnosed by Data Recovery Advisor. Every failure that is not closed has CRITICAL, HIGH, or LOW status. You can manually change the status of HIGH and LOW failures with the CHANGE command.
✗	failure status	The status of a failure diagnosed by Data Recovery Advisor. Every failure has OPEN or CLOSED status.
✗	file section	A contiguous range of blocks in a data file. A multisection backup processes a large file in parallel by copying each section to a separate backup piece.
!	flashback data archive	A historical repository of transactional changes to every record in a table for the duration of the record's lifetime. A flashback data archive enables you to use some Logical Flashback Features to transparently access historical data from far in the past.
✗	flashback database window	The range of SCNs for which there is currently enough flashback log data to support the `FLASHBACK DATABASE` command. The flashback database window cannot extend further back than the earliest SCN in the available flashback logs.
✗	flashback logs	Oracle-generated logs used to perform flashback database operations. The database can only write flashback logs to the fast recovery area.
✗	flashback retention target	A user-specified time or SCN that specifies how far into the past you want to be able to perform a flashback of the database.
✗	foreign archived redo log	An archived redo log received by a logical standby database for a LogMiner session. Unlike normal archived logs, foreign archived logs have a different DBID. For this reason, they cannot be backed up or restored on a logical standby database.
✗	foreign data file	A data file that does not belong to the target database, but is being plugged into the target database during a tablespace transport operation.
✗	foreign data file copy	A data file that was created when a cross-platform backup is restored in the destination database. It cannot be directly plugged in to the destination database because it is inconsistent.
✗	foreign tablespace	A set of foreign data files that comprise a tablespace in the source database. These foreign data files do not belong to the target database, but are being transported into the target database from the source database.
✗	fractured block	A block in which the header and footer are not consistent at a given SCN. In a user-managed backup, an operating system utility can back up a data file at the same time that DBWR is updating the file. It is possible for the operating system utility to read a block in a half-updated state, so that the block that is copied to the backup media is updated in its first half, while the second half contains older data. In this case, the block is fractured. For non-RMAN backups, the ALTER TABLESPACE ... BEGIN BACKUP or ALTER DATABASE BEGIN BACKUP command is the solution for the fractured block problem. When a tablespace is in backup mode, and a change is made to a data block, the database logs a copy of the entire block image before the change so that the database can reconstruct this block if media recovery finds that this block was fractured.
✗	full backup	A non-incremental RMAN backup. The word "full" does not refer to how much of the database is backed up, but to the fact that the backup is not incremental. Consequently, you can make a full backup of one data file.
✗	full resynchronization	An RMAN operation that updates the recovery catalog with all changed metadata in the database's control file. You can initiate a full catalog resynchronization by issuing the RMAN command RESYNC CATALOG. (It is rarely necessary to use RESYNC CATALOG because RMAN automatically performs resynchronizations when needed.)
✗	fuzzy file	A data file that contains at least one block with an SCN greater than or equal to the checkpoint SCN in the data file header. Fuzzy files are possible because database writer does not update the SCN in the file header with each file block write. For example, this situation occurs when Oracle updates a data file that is in backup mode. A fuzzy file that is restored always requires media recovery.
✗	guaranteed restore point	A restore point for which the database is guaranteed to retain the flashback logs for an Oracle Flashback Database operation. Unlike a normal restore point, a guaranteed restore point does not age out of the control file and must be explicitly dropped. Guaranteed restore points use space in the fast recovery area, which must be defined. hot backup See online backup
✗	hot backup mode	See backup mode
✗	incarnation	A separate version of a database. The incarnation of the database changes when you open it with the RESETLOGS option, but you can recover backups from a prior incarnation so long as the necessary redo is available.
✗	inconsistent backup	A backup in which some files in the backup contain changes that were made after the files were checkpointed. This type of backup needs recovery before it can be made consistent. Inconsistent backups are usually created by taking online database backups. You can also make an inconsistent backup by backing up data files while a database is closed, either: Immediately after the crash of an Oracle instance (or, in an Oracle RAC configuration, all instances) After shutting down the database using SHUTDOWN ABORT Inconsistent backups are only useful if the database is in ARCHIVELOG mode and all archived redo logs created since the backup are available. See Also: consistent backup, online backup, system change number (SCN), whole database backup
✗	incremental backup	An RMAN backup in which only modified blocks are backed up. Incremental backups are classified by level. A level 0 incremental backup performs the same function as a full backup in that they both back up all blocks that have ever been used. The difference is that a full backup does not affect blocks backed up by subsequent incremental backups, whereas an incremental backup affects blocks backed up by subsequent incremental backups. Incremental backups at level 1 back up only blocks that have changed since previous incremental backups. Blocks that have not changed are not backed up. An incremental backup can be either a differential incremental backup or a cumulative incremental backup.
✗	incremental forever	After a full backup, only incremental backups are stored. This allows for faster recovery because the current image copy of the database is readily available.
✗	incrementally updated backup	An RMAN data file copy that is updated by an incremental backup. An effective backup strategy is to copy a data file, make an incremental backup, and then merge the incremental backup into the image copy. This strategy reduces the time required for media recovery because the image copy is updated with the latest data block changes.
✗	instance failure	The termination of an Oracle instance due to a hardware failure, Oracle internal error, or SHUTDOWN ABORT statement. Crash or instance recovery is always required after an instance failure.
✗	instance recovery	In an Oracle RAC configuration, the application of redo data to an open database by an instance when this instance discovers that another instance has crashed. See Also: recover
✗	interblock corruption	A type of block corruption in which the corruption occurs between blocks rather than within the block itself. This type of corruption can only be logical corruption.
✗	intrablock corruption	A type of block corruption in which the corruption occurs within the block itself. This type of corruption can be either a physical corruption or logical corruption. level 0 incremental backup An RMAN incremental backup that backs up all data blocks in the data files being backed up. An incremental backup at level 0 is identical in content to a full backup, but unlike a full backup the level 0 backup is considered a part of the incremental backup strategy.
✗	level of multiplexing	The number of input files simultaneously read and then written into the same RMAN backup piece.
✗	local user	In a multitenant container database (CDB), any user that is not a common user. A local user exists in exactly one PDB.
✗	LogMiner	A utility that enables log files to be read, analyzed, and interpreted by SQL statements. See Also: archived redo log
✗	log switch	The point at which LGWR stops writing to the active redo log file and switches to the next available redo log file. LGWR switches when either the active log file is filled with redo records or you force a switch manually. See Also: redo log
✗	logical backup	A backup of database schema objects, such as tables. Logical backups are created and restored with the Oracle Data Pump Export utility. You can restore objects from logical backups using the Data Pump Import utility.
✗	logical corruption	A type of corruption in which the block has a valid checksum, the header and footer match, and so on, but the contents are logically inconsistent.
✗	long-term backup	A backup that you want to exclude from a backup retention policy, but want to record in the recovery catalog. Typically, long-term backups are snapshots of the database that you may want to use in the future for report generation.
✗	lost write	A write to persistent storage that the database believes has occurred based on information from the I/O subsystem, when in fact the write has not occurred.
✗	mean time to recover (MTTR)	The time required to perform recovery.
✗	media failure	Damage to the disks containing any of the files used by Oracle, such as the data files, archived redo log files, or control file. When Oracle detects media failure, it takes the affected files offline. See Also: media recovery
!	media management
✗	media management catalog	A catalog of records maintained by a media management software. This catalog is completely independent from the RMAN recovery catalog.
✗	media management library	A software library that RMAN can use to back up to tertiary storage. An SBT interface conforms to a published API and is supplied by a media management vendor. Oracle Secure Backup Backup includes an SBT interface for use with RMAN.
✗	media management software	An Oracle or third-party software library that integrates with Recovery Manager so that database backups can be written directly to SBT devices.
✗	media manager multiplexing	Multiplexing in which the media management software rather than RMAN manages the mixing of blocks during an RMAN backup. One type of media manager multiplexing occurs when the media manager writes the concurrent output from multiple RMAN channels to a single sequential device. Another type occurs when a backup mixes database files and non-database files on the same tape.
✗	media recovery	The application of redo or incremental backups to a restored backup data file or individual data block. When performing media recovery, you can recover a database, tablespace, data file, or set of blocks within a data file. media recovery can be either complete recovery (in which all changes in the redo logs are applied) or incomplete recovery (in which only changes up to a specified point in time are applied). media recovery is only possible when the database is in ARCHIVELOG mode. See Also: block media recovery, recover
✗	mirroring	Maintaining identical copies of data on one or more disks. Typically, mirroring is performed on duplicate hard disks at the operating system level, so that if one disk is unavailable, the other disk can continue to service requests without interruptions. When mirroring files, Oracle Database writes once while the operating system writes to multiple disks. When multiplexing files, Oracle Database writes the same data to multiple files. MTTR See mean time to recover (MTTR)
✗	multiplexed backup set	A backup set that contains blocks from multiple input files. For example, you could multiplex 10 data files into one backup set. Only whole files, never partial files, are included in a backup set.
✗	multiplexing	The meaning of the term depends on which files are multiplexed. Online redo logs: The automated maintenance of multiple identical copies of the online redo log. Control file: The automated maintenance of multiple identical copies of a database control file. Backup set: The RMAN technique of reading database files simultaneously from the disks and then writing the blocks to the same backup piece. Archived redo logs: The Oracle archiver process can archive multiple copies of a redo log. See Also: mirroring
✗	multisection backup	An RMAN backup set in which each backup piece contains a file section, which is a contiguous range of blocks in a data file. A multisection backup set contains multiple backup pieces, but a backup set never contains only a part of a data file. You create a multisection backup by specifying the SECTION SIZE parameter on the BACKUP command. An RMAN channel can process each file section independently, either serially or in parallel. Thus, in a multisection backup, multiple channels can back up a single file.
✗	multitenant architecture	The architecture that enables an Oracle database to function as a multitenant container database (CDB).
✗	multitenant container database (CDB)	See CDB
✗	native transfer rate	In a tape drive, the speed of writing to a tape without compression. This speed represents the upper limit of the backup rate.
✗	NOARCHIVELOG mode	The mode of the database in which Oracle does not require filled online redo logs to be archived before they can be overwritten. Specify the mode at database creation or change it with the ALTER DATABASE NOARCHIVELOG command. If you run in NOARCHIVELOG mode, it severely limits the possibilities for recovery of lost or damaged data. See Also: archived redo log, ARCHIVELOG mode
✗	non-CDB	An Oracle Database that is not a multitenant container database (CDB). All Oracle Databases created using Oracle Database 11g Release 2 (11.2) or earlier versions are non-CDBs.
✗	noncircular reuse records	Control file records containing critical information needed by the Oracle database. These records are never automatically overwritten. Some examples of information in noncircular reuse records include the locations of data files and online redo logs. See Also: circular reuse records
✗	normal restore point	A label for an SCN or time. For commands that support an SCN or time, you can often specify a restore point. Normal restore points exist in the circular list and can be overwritten in the control file. However, if the restore point pertains to an archival backup, then it is preserved in the recovery catalog.
✗	obsolete backup	A backup that is not needed to satisfy the current backup retention policy. For example, if your retention policy dictates that you must maintain one backup of each data file, but you have two backups of data file 1, then the second backup of data file 1 is considered obsolete.
✗	offline normal	A tablespace is offline normal when taken offline with the ALTER TABLESPACE ... OFFLINE NORMAL statement. The data files in the tablespace are checkpointed and do not require recovery before being brought online. If a tablespace is not taken offline normal, then its data files must be recovered before being brought online.
✗	offsite backup	An SBT backup that requires retrieval by the media management software before RMAN can restore it. You can list offsite backups with RESTORE ... PREVIEW.
✗	online backup	A backup of one or more data files taken while a database is open and the data files are online.
✗	online redo log	The online redo log is a set of two or more files that record all changes made to the database. Whenever a change is made to the database, Oracle generates a redo record in the redo buffer. The LGWR process writes the contents of the redo buffer into the online redo log. The current online redo log is the one being written to by LGWR. When LGWR gets to the end of the file, it performs a log switch and begins writing to a new log file. If you run the database in ARCHIVELOG mode, then each filled online redo log file must be copied to one or more archiving locations before LGWR can overwrite them. See Also: archived redo log
✗	online redo log group	The Oracle online redo log consists of two or more online redo log groups. Each group contains one or more identical online redo log members. An online redo log member is a physical file containing the redo records.
✗	online redo log member	A physical online redo log file within an online redo log group. Each log group must have one or more members. Each member of a group is identical. operating system backup See user-managed backup
✗	operating system backup and recovery	See user-managed backup and recovery
✗	Oracle Enterprise Manager Cloud Control	The primary product for managing your database is Oracle Enterprise Manager Cloud Control (Cloud Control), a Web-based interface. After you have installed the Oracle Database software, created or upgraded a database, and configured the network, you can use Cloud Control to manage your database. Cloud Control also provides an interface for performance advisors and for Oracle utilities such as SQL*Loader and Recovery Manager (RMAN).
✗	Oracle Flashback Database	The return of the whole database to a prior consistent SCN by the FLASHBACK DATABASE command in RMAN or SQL. A database flashback is different from traditional media recovery because it does not involve the restore of physical files, instead restoring your current data files to past states using saved images of changed data blocks. This feature uses flashback logs and archived redo logs.
✗	Oracle Secure Backup	An Oracle media manager that supplies reliable data protection through file system backup to tape. The Oracle Secure Backup SBT interface also enables you to use RMAN to back up Oracle databases. All major tape drives and tape libraries in SAN, Gigabit Ethernet, and SCSI environments are supported.
✗	Oracle-suggested backup strategy	A backup strategy available through a wizard in Oracle Enterprise Manager. The strategy involves periodically applying a level 1 incremental backup to a level 0 backup to create an incremental forever. If run daily, this strategy provides 24 hour point-in-time recovery from disk.
✗	Oracle VSS writer	A service on Windows systems that acts as coordinator between an Oracle Database instance and other Volume Shadow Copy Service (VSS) components, enabling data providers to create a shadow copy of files managed by the Oracle instance. For example, the Oracle VSS writer can place data files in hot backup mode to provide a recoverable copy of these data files in a shadow copy set.
✗	orphaned backups	Backups that were not made in the direct ancestral path of the current incarnation of the database. Orphaned backups cannot be used in the current incarnation.
✗	parallel recovery	A form of recovery in which several processes simultaneously apply changes from redo log files. The RECOVERY_PARALLELISM initialization parameter determines the level of parallelism for instance and crash recovery. You can use the PARALLEL and NOPARALLEL options of the RECOVER command to control parallelism for media recovery. Oracle Database automatically chooses the optimum degree of recovery parallelism. Usually, manually setting the level of parallelism for instance, crash, or media recovery is not recommended or necessary.
✗	parent incarnation	The database incarnation from which the current incarnation branched following an OPEN RESETLOGS operation.
✗	partial resynchronization	A type of resynchronization in which RMAN transfers data about archived logs, backup sets, and data file copies from the target control file to the recovery catalog.
✗	password file	A file created by the ORAPWD command, and required if you want to connect using the SYSDBA or SYSBACKUP privilege over a network. For details on password files, see the Oracle Database Administrator's Guide.
✗	PDB	In a multitenant container database (CDB), a portable collection of schemas, schema objects, and nonschema objects that appears to an Oracle Net client as a non-CDB. PDB restore point An alias for an SCN or a point in time in a particular pluggable database (PDB). A PDB restore point is applicable only to the PDB in which it is defined and cannot be used to perform operations either on other PDBs or the CDB.
✗	physical backup	A backup of physical files. A physical backup contrasts with a logical backup such as a table export.
✗	physical corruption	A type of corruption in which the database does not recognize a corrupt block. The database may not recognize the block because the checksum is invalid, the block contains all zeros, or the header and footer of the block do not match.
✗	physical schema	The data files, control files, and redo logs in a database at a given time. Issue the RMAN REPORT SCHEMA command to obtain a list of tablespaces and data files.
✗	physical standby database	A copy of a production database that you can use for disaster protection. pluggable database (PDB) See PDB
✗	problem	A critical error in the database that is recorded in the Automatic Diagnostic Repository (ADR). Critical errors include internal errors and other severe errors. Each problem has a problem key, which is a set of attributes that describe the problem. The problem key includes the ORA error number, error parameter values, and other information.
✗	proxy copy	A backup in which the media management software manages the transfer of data between the media storage device and disk during RMAN backup and restore operations.
✗	raw device	A disk or partition without a file system. Thus, you cannot use ls, Windows Explorer, and so on to view their contents. The raw partition appears to Oracle Database as a single file.
✗	recover	To recover a database file or a database is typically to perform media recovery, crash recovery, or instance recovery. This term can also be used generically to refer to reconstructing or re-creating lost data by any means. See Also: complete recovery, incomplete recovery
✗	recovery	When used to refer to a database file or a database, the application of redo data or incremental backups to database files to reconstruct lost changes. The three types of recovery are instance recovery, crash recovery, and media recovery. Oracle Database performs the first two types of recovery automatically using online redo records; only media recovery requires you to restore a backup and issue commands. See Also: complete recovery, incomplete recovery
✗	recovery catalog database	An Oracle Database that contains a recovery catalog schema.
✗	recovery catalog schema	The recovery catalog database schema that contains the recovery catalog tables and views.
✗	recovery set	One or more tablespaces that are being recovered to an earlier point in time during tablespace point-in-time recovery (TSPITR). After TSPITR, all database objects in the recovery set have been recovered to the same point in time. See Also: auxiliary set
✗	retention window	A recovery window is one type of RMAN backup retention policy, in which the DBA specifies a period of time and RMAN ensures retention of backups and archived redo logs required for point-in-time recovery to any time during the retention window. The interval always ends with the current time and extends back in time for the number of days specified by the user. For example, if the retention policy is set for a retention window of seven days, and the current time is 11:00 AM on Tuesday, RMAN retains the backups required to allow point-in-time recovery back to 11:00 AM on the previous Tuesday.
✗	recycle bin	A data dictionary table containing information about dropped objects. Dropped tables and any associated objects such as indexes, constraints, nested tables, and so on are not removed and still occupy space. The Flashback Drop feature uses the recycle bin to retrieve dropped objects.
✗	redo log	A redo log can be either an online redo log or an archived redo log. The online redo log is a set of two or more redo log groups that records all changes made to Oracle data files and control files. An archived redo log is a copy of an online redo log that has been written to an offline destination.
✗	redo log group	Each online redo log member (which corresponds to an online redo log file) belongs to a redo log group. Redo log groups contain one or more members. A redo log group with multiple members is called a multiplexed redo log group. The contents of all members of a redo log group are identical.
✗	redo thread	The redo generated by an instance. If the database runs in a single instance configuration, then the database has only one thread of redo.
✗	redundancy	In a retention policy, the setting that determines many copies of each backed-up file to keep. A redundancy-based retention policy is contrasted with retention policy that uses a retention window.
✗	redundancy set	A set of backups enabling you to recover from the failure or loss of any Oracle Database file.
✗	registration	In RMAN, the execution of a REGISTER DATABASE command to record the existence of a target database in the recovery catalog. A target database is uniquely identified in the catalog by its DBID. You can register multiple databases in the same catalog, and also register the same database in multiple catalogs.
✗	repair	For Data Recovery Advisor, a repair is an action or set of actions that fixes one or more failures. Examples repairs include block media recovery, data file media recovery, Oracle Flashback Database, and so on.
✗	repair option	For Data Recovery Advisor, one possible technique for repairing a failure. Different repair options are intended to fix the same problem, but represent different advantages and disadvantages in terms of repair time and data loss.
✗	RESETLOGS	A technique for opening a database that archives any current online redo logs (if using ARCHIVELOG mode), resets the log sequence number to 1, and clears the online redo logs. An ALTER DATABASE OPEN RESETLOGS statement begins a new database incarnation. The starting SCN for the new incarnation, sometimes called the RESETLOGS SCN, is the incomplete recovery SCN of the media recovery preceding the OPEN RESETLOGS, plus one. An ALTER DATABASE OPEN RESETLOGS statement is required after incomplete recovery or recovery with a backup control file. An OPEN RESETLOGS operation does not affect the recoverability of the database. Backups from before the OPEN RESETLOGS operation remain valid and can be used along with backups taken after the OPEN RESETLOGS operation to repair any damage to the database.
✗	resilver a split mirror	The process of making the contents of a split mirror identical with the contents of the storage devices from which the mirror was split. The operating system or the hardware managing the mirror refreshes a broken mirror from the half that is up-to-date and then maintains both sides of the mirror.
✗	restartable backup	The feature that enables RMAN to back up only those files that have not been backed up since a specified date. The unit of restartability is last completed backup set or image copy. You can use this feature after a backup fails to back up the parts of the database missed by the failed backup.
✗	restore	The replacement of a lost or damaged file with a backup. You can restore files either with commands such as UNIX cp or the RMAN RESTORE command.
✗	restore failover	The automatic search by RMAN for usable backups in a restore operation if a corrupted or inaccessible backup is found.
✗	restore optimization	The default behavior in which RMAN avoids restoring data files from backup when possible.
✗	restore point	A user-defined a name associated with an SCN of the database corresponding to the time of the creation of the restore point. A restore point can be a guaranteed restore point or a normal restore point.
✗	resynchronization	The operation that updates the recovery catalog with current metadata from the target database control file. You can initiate a full resynchronization of the catalog by issuing a RESYNC CATALOG command. A partial resynchronization transfers information to the recovery catalog about archived redo log files, backup sets, and data file copies. RMAN resynchronizes the recovery catalog automatically when needed. retention policy. See backup retention policy
✗	reverse resynchronization	In a Data Guard environment, the updating of a primary or standby database control file with metadata obtained from the recovery catalog. For example, if you configure persistent RMAN settings for a standby database that is not the connected target database, then RMAN performs a reverse resynchronization the next time RMAN connects as target to the standby database. In this way, the recovery catalog keeps the metadata in the control files in a Data Guard environment up to date.
✗	rollback segments	Database segments that record the before-images of changes to the database.
✗	rolling back	The use of rollback segments to undo uncommitted changes applied to the database during the rolling forward stage of recovery.
✗	rolling forward	The application of redo records or incremental backups to data files and control files to recover changes to those files. See Also: rolling back
✗	root	In a multitenant container database (CDB), a system-supplied set of schemas, schema objects, and non-schema objects that functions as the parent for PDBs. Every CDB has only one root and all PDBs belong to the root.
✗	RUN block	A series of RMAN commands commands that are executed sequentially.
✗	shadow copy	In the Volume Shadow Copy Service (VSS) infrastructure on Windows, a consistent snapshot of a component or volume.
✗	snapshot control file	A copy of a database control file created in an operating system-specific location by Recovery Manager. RMAN creates the snapshot control file so that it has a consistent version of a control file to use when either resynchronizing the recovery catalog or backing up the control file.
✗	source database	The database that you are copying when you create a duplicate database. When transporting data to another platform, the source database is the database that contains the data that is to be transported.
✗	source host	The host on which a source database resides.
✗	source platform	When transporting data, the platform on which the source database is running. The source database contains the data to be transported to a destination database running on a different platform. sparse backup An RMAN backup that backs up one or more sparse data files. For each sparse data file, a full backup of the shadow file (not the base file) is created. sparse database A database that contains one or more sparse data files. sparse data file A logical Oracle object that is created as the shadow of a base data file. The base data file is read-only. The sparse data file is read-write and contains the updates made to the base data file.
✗	split mirror backup	A backup of database files that were previously mirrored. Some third-party tools enable you to use mirroring a set of disks or logical devices, that is, maintain an exact duplicate of the primary data in another location. Splitting a mirror involves separating the file copies so that you can use them independently. With the ALTER SYSTEM SUSPEND/RESUME database feature, you can suspend I/O to the database, split the mirror, and make a backup of the split mirror.
✗	stored script	A sequence of RMAN commands commands stored in the recovery catalog. Stored scripts can be global or local. Global scripts can be shared by all databases registered in the recovery catalog.
✗	synchronous I/O	A server process can perform only one task at a time while RMAN is either reading or writing data.
✗	system change number (SCN)	A stamp that defines a committed version of a database at a point in time. Oracle assigns every committed transaction a unique SCN.
✗	tablespace destination	In a transportable tablespace operation, the location on disk which (by default) contains the data file copies and other output files when the tablespace transport command completes.
✗	tablespace point-in-time recovery (TSPITR)	The recovery of one or more non-SYSTEM tablespaces to a noncurrent time. You use RMAN to perform TSPITR.
✗	tag	Identifier for an RMAN backup. If you generate a backup set, then the tag is assigned to each backup piece rather than to the backup set. If you do not specify a tag for a backup, then RMAN assigns one automatically.
✗	target database	In an RMAN environment, the database to which you are connected as TARGET. The target database is the database on which you are performing RMAN operations.
✗	target host	The computer on which a target database resides.
✗	target instance	In an RMAN environment, the instance associated with a target database.
✗	temp file	A file that belongs to a temporary tablespace and is created with the TEMPFILE option. Temporary tablespaces cannot contain permanent database objects such as tables, and are typically used for sorting. Because temp files cannot contain permanent objects, RMAN does not back them up. RMAN does keep track of the locations of temp files in the control file, however, and during recovery re-creates the temp files as needed at those locations.
✗	transport script	A script generated by the CONVERT DATABASE command. This script contains SQL statements used to create the new database on the destination platform.
✗	transportable tablespace	A feature that transports a set of tablespaces from one database to another, or from one database to itself. Transporting a tablespace into a database is like creating a tablespace with loaded data.
✗	transportable tablespace set	Data files for the set of tablespaces in a transportable tablespace operation, and an export file containing metadata for the set of tablespaces. You use Data Pump Export to perform the export of metadata.
✗	trial recovery	A simulated recovery initiated with the RECOVER ... TEST command in RMAN or SQL*Plus. A trial recovery applies redo in a way similar to normal media recovery, but it never writes its changes to disk and it always rolls back its changes. Trial recovery occurs only in memory.
✗	unused block compression	A feature by which RMAN reduces the size of data file backup sets by skipping data blocks. RMAN always skips blocks that have never been used. Under certain conditions, which are described in the BACKUP AS BACKUPSET entry in Oracle Database Backup and Recovery Reference, RMAN also skips previously used blocks that are not currently being used.
✗	user-managed backup	A backups made using a non-RMAN method, for example, using an operating system utility. For example, you can make a user-managed backup by running the cp command on Linux or the COPY command on Windows. A user-managed backup is also called an operating system backup.
✗	user-managed backup and recovery	A backup and recovery strategy for an Oracle Database that does not use RMAN. This term is equivalent to operating system backup and recovery. You can back up and restore database files using operating system utilities (for example, the cp command in UNIX), and recover using the SQL*Plus RECOVER command.
✗	validation	In an RMAN context, a test that checks database files for block corruption or checks a backup set to determine whether it can be restored. RMAN can check for both physical and logical block corruption.
✗	virtual private catalog	A subset of the metadata in a base recovery catalog to which a database user is granted access. The owner of a base recovery catalog can grant or revoke restricted access to the recovery catalog to other database users. Each restricted user has full read/write access to his own virtual private catalog.
✗	Volume Shadow Copy Service (VSS)	An infrastructure on Windows server platforms that enables requestors, writers, and providers to participate in the creation of a consistent snapshot called a shadow copy. The VSS service uses well-defined COM interfaces. See Oracle Database Platform Guide for Microsoft Windows to learn how to use RMAN with VSS.
✗	whole database backup	A backup of the control file and all data files that belong to a database.
✗	Zero Data Loss Recovery Appliance (Recovery Appliance)	An enterprise-level, cloud-scale Engineered System, that provides a single, centralized repository for backups of all your Oracle Databases. You can use RMAN commands to backup your target database to Recovery Appliance.