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Oracle Hybrid Columnar Compression

Required platforms

HCC needs a supported Oracle platform such as Exadata, SuperCluster, ZFS Storage Appliance or FS Flash Storage System.

Best use of HCC

HCC is useful if data is bulk loaded and then queried (with little or no DML statements after bulk loading the data).

Bulk loads are often found in dataware houses: inserts with /*+ append */ hint, parallel dml, direct path SQL*LDR, create table as select statements.

HCC should also be used for relational data, not for unstructred LOBs.

Compression Units (CU)

In HCC, table data is split into compression units that are larger than database blocks.

Within a CU, data is laid out in columns rather than by rows.

SQL - Create table

create table ... ( columns) COMPRESS FOR QUERY   LOW ;
create table ... ( columns) COMPRESS FOR QUERY   HIGH;
create table ... ( columns) COMPRESS FOR ARCHIVE LOW ;
create table ... ( columns) COMPRESS FOR ARCHIVE HIGH;

LONG data type