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COMPRESS FOR ALL OPERATIONS generates lot of redo (Doc ID 829068.1)

Last updated on FEBRUARY 25, 2019

Applies to:

Oracle Database - Enterprise Edition - Version 11.1.0.7 and later
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Cloud Machine - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Oracle Database Backup Service - Version N/A and later
Information in this document applies to any platform.

Symptoms

COMPRESS FOR ALL OPERATIONS generates significantly more redo than NOCOMPRESS or, even COMPRESS (and load data with direct load)

With "COMPRESS FOR ALL OPERATIONS" database calls the code to try to compress the current block for all operations. The undo for such compression is a before block image.Hence the redo with "COMPRESS FOR ALL OPERATIONS" includes extra redo for the UNDO (before images) of blocks.

So even if the effect of the attempt to compress the block is minimal undo will have to be dumped (before image) for that attempt.

Changes

This behavior is specific for 11g (and onwards) as COMPRESS FOR ALL OPERATIONS is not available on pre-11g releases.

Cause

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In this Document
Symptoms
Changes
Cause
Solution
References

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