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https://issues.apache.org/jira/browse/HBASE-5257?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13483865#comment-13483865
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Lars Hofhansl commented on HBASE-5257:
--------------------------------------
I like the patch. It is a simple yet effective solution for this, which can
also be used by other filters in the future.
> Allow filter to be evaluated after version handling
> ---------------------------------------------------
>
> Key: HBASE-5257
> URL: https://issues.apache.org/jira/browse/HBASE-5257
> Project: HBase
> Issue Type: Improvement
> Reporter: Lars Hofhansl
> Fix For: 0.96.0
>
> Attachments: 5257-trunk.txt, HBASE-5257-0.92.txt,
> HBASE-5257-0.92.txt, HBASE-5257-0.94.txt, HBASE-5257-0.94.txt
>
>
> There are various usecases and filter types where evaluating the filter
> before version are handled either do not make sense, or make filter handling
> more complicated.
> Also see this comment in ScanQueryMatcher:
> {code}
> /**
> * Filters should be checked before checking column trackers. If we do
> * otherwise, as was previously being done, ColumnTracker may increment
> its
> * counter for even that KV which may be discarded later on by Filter.
> This
> * would lead to incorrect results in certain cases.
> */
> {code}
> So we had Filters after the column trackers (which do the version checking),
> and then moved it.
> Should be at the discretion of the Filter.
> Could either add a new method to FilterBase (maybe excludeVersions() or
> something). Or have a new Filter wrapper (like WhileMatchFilter), that should
> only be used as outmost filter and indicates the same (maybe
> ExcludeVersionsFilter).
> See latest comments on HBASE-5229 for motivation.
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