Inserts on HCC Compressed Tables Can Be Significantly Slower in 12.2 Compared to 11.2 (Doc ID 2469912.1)

Last updated on JANUARY 16, 2020

Applies to:

Symptoms

• Significantly slower insert performance with 12.2 (and above) on HCC compressed tables/partitions
• Performance impact reported during conventional path inserts on HCC compressed tables/partitions
• Insert use cases include: SQL INSERT SELECT statement without the APPEND hint and array inserts from programmatic interfaces such as PL/SQL and the Oracle Call Interface (OCI) on HCC compressed tables/partitions

Changes

The introduction of support for HCC Compression for Array Inserts in Oracle Database 12.2.0.1.

Hybrid Columnar Compression (HCC) can now be used during array inserts into tables. This means that the SQL INSERT SELECT statement without the APPEND hint can use HCC, and array inserts from programmatic interfaces such as PL/SQL and the Oracle Call Interface (OCI) can use HCC. This feature is intended to make it easier to gain the benefits of HCC by enabling HCC when data is inserted without using direct path operations.

Cause

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