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https://issues.apache.org/jira/browse/PHOENIX-6115?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17187982#comment-17187982
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Lars Hofhansl commented on PHOENIX-6115:
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Hmm... To be effective it's a bit more complicated than that. It's not about
covered columns... When the index has any non-pk columns indexed, we could
avoid reading any rows relevant other than for delete mutations.
We are allowing deletes on immutable tables, so that we still need to delete
from the index in that case.
The patch above is correct, but it does not do what I intended. It only has any
effect when the index only re-arranges PK columns (for example for sorting).
It's still an improvement, but not what I intended.
> Avoid scanning prior row state for uncovered local indexes on immutable
> tables.
> -------------------------------------------------------------------------------
>
> Key: PHOENIX-6115
> URL: https://issues.apache.org/jira/browse/PHOENIX-6115
> Project: Phoenix
> Issue Type: Bug
> Reporter: Lars Hofhansl
> Priority: Major
> Attachments: 6115-master.txt
>
>
> Looking at the code I realized that we retrieve the prior row state even when
> is not necessary.
> Specifically it is not necessary when (a) the table is immutable and (b) the
> indexes does not include any covered columns.
> The unnecessary work is in part a consequence of the changes for global
> consistent indexing.
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