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Table Compression Count Statistic (Doc ID 1357738.1)

Last updated on AUGUST 04, 2018

Applies to:

Oracle Server - Enterprise Edition - Version: and later   [Release: 11.2 and later ]
Information in this document applies to any platform.


=== ODM Question ===

  We are in process of testing table compression feature with: compress for all operations, however we are trying to determine:

1. Why so much undo is being generated, we believe this is due to the before image of the block being retained in undo segment every time compression is applied to the block?

 Initially we ran few test which indicated, column: v$transaction.used_ublk (undo block) and statistic: heap block compress increased every time compression occurred.

2. What is the correct session level statistic that verifies "how many" times compression took place?

3. What is the difference between: HSC OLTP positive compress and heap block compress?


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