v$lock_type lists the available locks (aka enqueues)
select
name,
type,
description
from
v$lock_type
order by
lower(name);
--
-- ACD Relocation Gate Enqueue FG ACD relocation serialization
-- ACD Xtnt Info CIC FX serialize ACD relocation CIC
-- Active Session History Flushing SH To prevent multiple concurrent flushers
-- Advisor Framework AF This enqueue is used to serialize access to an advisor task
-- Alter Tablespace AT Serializes 'alter tablespace' operations
-- Analytic Workspace AW Synchronizes access to Analytic Workspace resources
-- Analytic Workspace Generation AG Synchronizes generation use of a particular workspace
-- AQ Notification Mail Host MH Lock used for recovery when setting Mail Host for AQ e-mail notifications
-- AQ Notification Mail Port ML Lock used for recovery when setting Mail Port for AQ e-mail notifications
-- AQ Notification No-Proxy XH Lock used for recovery when setting No Proxy Domains for AQ HTTP notifications
-- AQ Notification Proxy PH Lock used for recovery when setting Proxy for AQ HTTP notifications
-- AQ Notification Sender SF Lock used for recovery when setting Sender for AQ e-mail notifications
-- AQ Notification Watermark WA Lock used for recovery when setting Watermark for memory usage in AQ notifications
-- ASM Attributes Enque KQ Single Inst Sync of ASM attributes
-- ASM Cached Attributes KE Synchronization of ASM cached attributes
-- ASM Disk AU Lock AD Synchronizes accesses to a specific ASM disk AU
-- ASM Disk Group Modification DG Synchronizes accesses to ASM disk groups
-- ASM Disk Header HD Serializes accesses to ASM SGA data structures
-- ASM Disk Online Lock DO Synchronizes disk onlines and their recovery
-- ASM Enqueue AM ASM instance general-purpose enqueue
-- ASM Extent Fault Lock XL Keep multiple processes from faulting in the same extent chunk
-- ASM Extent Relocation Enqueue XQ ASM extent relocation
-- ASM Extent Relocation Lock RX Synchronizes relocating ASM extents
-- ASM File Access Lock FA Synchronizes accesses to open ASM files
-- ASM Freezing Cache Lock FZ Freezes ASM Cache for a diskgroup
-- ASM Group Block lock XB Prevents client diskgroup use during storage reconfiguration
-- ASM Instance Enqueue CM ASM instance and gate enqueue
-- ASM Local Disk Group DD Synchronizes local accesses to ASM disk groups
-- ASM Partnership and Status Table PT Gates inter-node synchronization of ASM PST metadata
-- ASM PST Signalling PM Signals inter-instance access to ASM PST metadata
-- ASM RBAL doorbell DQ Inter-RBAL process metadata invalidation notification
-- ASM Relocation Lock AR Protects locked extent pointers during ASM file relocation
-- ASM Rollback Recovery RB Serializes ASM rollback recovery operations
-- ASM volume locks AV id1 is for persistent DG number locking. id2 is for other volume serialization
-- Audit Partition ZA Lock held for adding partition to Aud table
-- Auto BMR AB A general class of locks used by auto BMR for various purposes
-- Auto Online Exadata disks XD Serialize Auto Management of Exadata disks
-- Auto Task Serialization TK Prevents more than one AutoTask Background Slave from being spawned
-- AWR Flush WF This enqueue is used to serialize the flushing of snapshots
-- AWR Purge WP This enqueue handles concurrency between purging and baselines
-- Backup/Restore BR Lock held by a backup/restore operation to allow other operations to wait for it
-- Being Written Redo Log WL Coordinates access to redo log files and archive logs
-- Block Change Tracking CT A general class of locks used by change tracking for various purposes
-- Block Repair/Resilvering RE Synchronizes block repair/mirror resilvering operations
-- BLOOM FILTER BF Synchronize access to a bloom filter in a parallel statement
-- Buffer Cache PreWarm PW Coordinates Direct Loads with Prewarmed cache buffers
-- Calibration CA Lock used by IO Calibration
-- Cleanup querycache registrations CQ Serializes access to cleanup client query cache registrations
-- clonedb bitmap file access BM synchronizes clonedb bitmap file operations
-- Compression Analyzer ZH Synchronizes analysis and insert into compression$, prevents multiple threads analyzing the same table during a load
-- Controlfile Transaction CF Synchronizes accesses to the controlfile
-- Cross-Instance Call Invocation CI Coordinates cross-instance function invocations
-- Cross-Instance Transaction TW Lock held by one instance to wait for transactions on all instances to finish
-- Cursor CU Recovers cursors in case of death while compiling
-- Data Guard Broker RF Synchronizes broker lock operation involving lock value
-- Database Mount/Open DM Enqueue held by foreground or DBWR to synchronize database mount/open with other operations
-- Database Suspend DS Prevents a database suspend during LMON reconfiguration
-- Datafile Online in RAC DF Enqueue held by foreground or DBWR when a datafile is brought online in RAC
-- DBFUS FU This enqueue is used to serialize the capture of the DB Feature Usage and High Water Mark Statistics
-- DbsDriver DB Synchronizes modification of database wide supplementallogging attributes
-- Default Temporary Tablespace DT Serializes changing the default temporary table space and user creation
-- Diana Versioning DV Synchronizes access to lower-version Diana (PL/SQL intermediate representation)
-- Direct Loader High Water Mark HV Lock used to broker the high water mark during parallel inserts
-- Direct Loader Index Creation DL Lock to prevent index DDL during direct load
-- Disk Group Chunk Mount FC controls access to an ACD chunk
-- Disk Group Recovery FR enqueue to control ASM recovery
-- Disk Group Redo Generation FT controls the privilege to generate redo in a thread
-- Diskgroup number generator DN Serializes Group number generations
-- Distributed Recovery DR Serializes the active distributed recovery operation
-- Distributed Transaction DX Serializes tightly coupled distributed transaction branches
-- DML TM Synchronizes accesses to an object
-- Edition Lock AE Prevent Dropping an edition in use
-- Encryption Wallet OW Serializes wallet initialization and access
-- FGA Partition ZF Lock held for adding partition to Fga table
-- File Group ZG Coordinates file group operations
-- File Mapping FM Synchronizes access to global file mapping state
-- File Object FP Synchronizes various File Object(FOB) operations
-- File Set / Dictionary Check FS Enqueue used to synchronize recovery and file operations or synchronize dictionary check
-- Flashback Database FD Coordinate flashback database
-- Flashback database log FL Synchronize access to flashback database log
-- Flashback Writer FW Coordinate RVWR on multiple instances
-- Format Block FB Ensures that only one process can format data blocks in auto segment space managed tablespaces
-- GES Deadlock Test AK Lock used for internal testing
-- GES Internal DI Coordinates Global Enqueue Service deadlock detection
-- GES Resource Remastering RM Coordinates Global Enqueue Service resource remastering
-- Global Context Action ZZ Lock held for updating Global context hash tables
-- Global Parameter PG Synchronizes global system parameter updates
-- Global Transaction Branch BB 2PC distributed transaction branch across RAC instances
-- Hash Queue HQ Synchronizes the creation of new queue IDs
-- In memory Dispenser DW Serialize in memory dispenser operations
-- In-Mem Temp Table Meta Creation IT Synchronizes accesses to a temp object's metadata
-- INSTANCE LOCK IZ Proctects the lock name space used by the instance
-- Instance Recovery IR Synchronizes instance recovery
-- Instance State IS Enqueue used to synchronize instance state changes
-- Instance Undo TA Serializes operations on undo segments and undo tablespaces
-- Internal IA
-- Internal Test XY Lock used for internal testing
-- Job Queue JQ Lock to prevent multiple instances from running a single job
-- Job Queue Date JD Synchronizes dates between job queue coordinator and slave processes
-- Job Scheduler JS Synchronizes accesses to the job cache
-- Kick Instance to Switch Logs KK Lock held by open redo thread, used by other instances to force a log switch
-- KSV slave startup PV Synchronizes slave start_shut
-- KSXA Test Affinity Dictionary AY Affinity Dictionary test affinity synchronization
-- ksz synch MX Used to synchronize storage server info across all nodes
-- KTCN REG enq CN Enqueue held for registrations for change notifications
-- KTF broadcast TE Serializes broadcasts for flushes to SMON_SCN_TIME
-- KTF map table enqueue TD Serializes updates and inserts to the SMON_SCN_TIME mapping table
-- KTFA Recovery FE Flashback archive Enqueue to serialize recovery
-- Kti blr lock IM Serializes block recovery for an IMU txn
-- KTSJ Slave Task Cancel SJ Serializes cancelling task executed by slave process
-- KTUCLO Master Slave enq CO Enqueue held for determining Master Slaves
-- Kupp Process Startup KP Synchronizes kupp process startup
-- Label Security IL Synchronizes accesses to internal label data structures
-- Label Security cache CL Synchronizes accesses to label cache and label tables
-- LDAP Parameter DP Synchronizes access to LDAP parameters
-- Library Cache Invalidation IV Synchronizes library cache object invalidations across instances
-- Library Cache Lock 1 L Synchronizes accesses to library cache objects
-- Library Cache Lock 2 E Synchronizes accesses to library cache objects
-- Library Cache Lock 3 V Synchronizes accesses to library cache objects
-- Library Cache Pin 1 N Synchronizes accesses to the contents of library cache objects
-- Library Cache Pin 2 G Synchronizes accesses to the contents of library cache objects
-- Library Cache Pin 3 Y Synchronizes accesses to the contents of library cache objects
-- LNS archiving log WR Coordinates access to logs by Async LNS and ARCH/FG
-- LOB KSI LOCK KL KSI lock for buffer cache and wgc concurrency
-- Log Lock TL Serializes threshold log table read and update
-- LogicalStandby SB Synchronizes Logical Standby metadata operations
-- LogMiner MN Synchronizes updates to the LogMiner dictionary and prevents multiple instances from preparing the same LogMiner session
-- LogWriter Standby WS Used by LogWriter to coordinate communication to standby databases
-- Master Key MK Serializes enc$ access
-- Materialized View JI Lock held during materialized view operations (like refresh, alter) to prevent concurrent operations on the same materialized view
-- Materialized View Flags RW Lock used when creating or readingmaterialized view flags in detail tables
-- Materialized View Log DDL MD Lock held during materialized view log DDL statements
-- Materialized View Refresh Log MS Lock held during materialized view refresh to setup MV log
-- Media Recovery MR Lock used to coordinate media recovery with other uses of datafiles
-- MMON restricted session MO Serialize MMON operations for restricted sessions
-- Multiple Object Checkpoint KO Coordinates checkpointing of multiple objects
-- Multiple Object Reuse RO Coordinates flushing of multiple objects
-- MultiWriter Object Access AO Synchronizes access to objects and scalar variables
-- MWIN Schedule MW This enqueue is used to serialize the calibration of the manageability schedules with the Maintenance Window
-- NID ID Lock held by a NID operation to allow other operations to wait for it
-- OLAPI Histories OQ Synchronizes access to olapi history resources
-- Online Datafile Move MV Synchronizes online datafile move operation or cleanup
-- Online DDLs OD Lock to prevent concurrent online DDLs
-- Outline Cache OC Synchronizes write accesses to the outline cache
-- Outline Name OL Synchronizes accesses to a particular outline name
-- Parameter PE Synchronizes system parameter updates
-- Password File PF Synchronizes accesses to the password file
-- Process Startup PR Synchronizes process startup
-- Property Lock PD Serializes property update
-- PX Process Reservation PS Parallel Execution Server Process reservation and synchronization
-- Queue Page HP Synchronizes accesses to queue pages
-- Queue table enqueue TQ Synchronizes access to queue table
-- Quiesce / Force Logging XR Lock held during database quiesce or for database force logging
-- RAC Encryption Wallet Lock RL RAC encryption wallet lock
-- RAC Load RD synchronize update of RAC load info
-- Reclaimable Space RS Lock held by a space reclaimable operation to allow other operations to wait for it
-- Redo Log Nab Computation RN Coordinates nab computations of online logs during recovery
-- Redo Thread RT Thread locks held by LGWR, DBW0, and RVWR to indicate mounted or open status
-- Remote PX Process Spawn Status PI Communicates remote Parallel Execution Server Process creation status
-- Resilver / Repair RP Enqueue held when resilvering is needed or when datablock is repaired from mirror
-- Result Cache: Enqueue RC Accessing a result in the result-set cache
-- Reuse Block Range CR Coordinates checkpointing of block range reuse
-- Rolling Migration RU Serilized rolling migration operations
-- Row Cache Q Coordinates updates and accesses to row cache objects
-- Runtime Fixed Table Purge TP Lock used for fixed runtime table purge and definition
-- SaveUndo Segment SU Serializes access to SaveUndo Segment
-- Scheduler KM Synchronizes various Resource Manager operations
-- Scheduler Master DBRM KD Determine DBRM master
-- Scheduler Plan KT Synchronizes accesses to the current Resource Manager plan
-- Segment High Water Mark HW Lock used to broker the high water mark during parallel inserts
-- Sequence Cache SQ Lock to ensure that only one process can replenish the sequence cache
-- Sequence Ordering SV Lock to ensure ordered sequence allocation in RAC mode
-- Serialize Lock request SL Request serialization to LCK0
-- Service Operations AS Synchronizes new service activation
-- Session Migration SE Lock used by transparent session migration
-- Shared Object SO Synchronizes access to Shared Object(PL/SQL Shared Object Manager)
-- Shrink Segment SK Serialize shrink of a segment
-- SMON Serialization SM Lock to check SMON global work in RAC
-- Sort Segment SS Ensures that sort segments created during parallel DML operations aren't prematurely cleaned up
-- Space Transaction ST Synchronizes space management activities in dictionary-managed tablespaces
-- Spare Enqueue SP Spare enqueue for one-off backports
-- SPM Autopurge AP This enqueue is used to serialize the purging of SQL plan baselines
-- SQL STATEMENT QUEUE JX synchronize SQL statement queue operations
-- SQL Tuning Base Existence Cache TB Synchronizes writes to the SQL Tuning Base Existence Cache
-- Streams Table Instantiation SI Prevents muiltiple streams table instantiations
-- Suspend Writes SW Coordinates the 'alter system suspend' operation
-- Synchronized Replication SR Coordinates replication / streams operations
-- System Change Number SC Coordinates system change number generation on multiple instances
-- Tablespace TT Serializes DDL operations on tablespaces
-- Tablespace Checkpoint TC Lock held to guarantee uniqueness of a tablespace checkpoint
-- Temp Object TO Synchronizes DDL and DML operations on a temp object
-- Temporary File TF Serializes dropping of a temporary file
-- Temporary Segment TS Serializes accesses to temp segments
-- TEXT: Generic Lock OT Generic Lock on CTX index
-- TEXT: Index Specific Lock CX Index Specific Lock on CTX index
-- Threshold Chain TH Serializes threshold in-memory chain access
-- Transaction TX Lock held by a transaction to allow other transactions to wait for it
-- Transportable Tablespace PL Coordinates plug-in operation of transportable tablespaces
-- Undo Segment US Lock held to perform DDL on the undo segment
-- User-defined UL Lock used by user applications
-- wallet_set_mkey RK Serializes wallet master key rekey
-- WLM Plan Operations WM Synchronizes new WLM Plan activation
-- Workload Capture and Replay RR Prevents concurrent invokers of DBMS_WORKLOAD_*
-- Write gather local enqueue WG Long term lock on wgc file state
-- XDB Configuration XC Synchronization access to XDB configuration