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https://issues.apache.org/jira/browse/DERBY-2912?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Dag H. Wanvik updated DERBY-2912:
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Derby Categories: [Performance]
> Reduce checkpoint cost in truncateEnd phase of SYSCS_INPLACE_COMPRESS_TABLE
> ---------------------------------------------------------------------------
>
> Key: DERBY-2912
> URL: https://issues.apache.org/jira/browse/DERBY-2912
> Project: Derby
> Issue Type: Improvement
> Components: Store
> Reporter: Daniel John Debrunner
> Priority: Minor
>
> The truncate phase of SYSCS_INPLACE_COMPRESS_TABLE always performs a
> checkpoint per container. For any table this is likely to mean a number of
> checkpoints (one per index and one for the base table).
> Potential improvements are:
> 1) Only perform the checkpoint (and the clean of the allocation cache) if
> the truncate will actually free some space up.
> 2) Perform the checkpoint once for a table, not once per container.
> 3) Don;t perform a complete checkpoint, just flush the pages for the
> table/container being truncated.
> 1) Seems fairly possible, I have no idea if the others are.
> This affects the JUnit tests which perform a inplace compress on SYSDEPENDS,
> even with no space to free up the inplace compress takes about 0.5 seconds
> and upto two seconds with changes (even on a fairly small table).
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