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Table Compression Count Statistic (Doc ID 1357738.1)

Last updated on FEBRUARY 21, 2024

Applies to:

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


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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