Performance Degradation Due to Row Chaining on Compressed Table (Doc ID 1204203.1)

Last updated on FEBRUARY 02, 2017

Applies to:

Oracle Database - Enterprise Edition - Version 11.2.0.1.0 and later
Information in this document applies to any platform.

Symptoms


When table compression or tablespace compression are used, row chaining occurs after an update.  However, when the same table is not compressed and resides in a non compressed tablespace row chaining does not occur.  This appears to be affecting performance.

SQL> select table_name, tablespace_name, compression, compress_for from
user_tables where table_name = 'COMPRESSION_TEST';

TABLE_NAME                     TABLESPACE_NAME                COMPRESS
------------------------------ ------------------------------ --------
COMPRESS_FOR
------------
COMPRESSION_TEST               COMPRESS_TEST_TS               ENABLED
OLTP

After update:

SQL> select count(*) from comp_chained_rows;

  COUNT(*)
----------
   1762368


When the same table is used without compression:

select table_name, tablespace_name, compression, compress_for from
user_tables where table_name = 'COMPRESSION_TEST';
TABLE_NAME                     TABLESPACE_NAME                COMPRESS
------------------------------ ------------------------------ --------
COMPRESS_FOR
------------
COMPRESSION_TEST               NOCOMPRESS_TEST_TS             DISABLED


SQL> SQL> select count(*) from comp_chained_rows;

  COUNT(*)
----------
         0

Cause

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