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https://issues.apache.org/jira/browse/HBASE-6427?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13424663#comment-13424663
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Andrew Purtell commented on HBASE-6427:
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bq. I personally haven't seen chained scanners in action. If we don't think
through how chained scanners work, I wouldn't expect HBase users to use this
mechanism.
Ted, this is a great comment, because I think it illustrates an incorrect
approach to CP API design. (Not meant to be a criticism of you. :-)) CPs are
targeted as much for HBase developers as they might be for users. The
fundamental goal of CPs is to avoid needing to patch core HBase code for
implementing new features or researching design alternatives.
> Pluggable compaction policies via coprocessors
> ----------------------------------------------
>
> Key: HBASE-6427
> URL: https://issues.apache.org/jira/browse/HBASE-6427
> Project: HBase
> Issue Type: New Feature
> Reporter: Lars Hofhansl
> Assignee: Lars Hofhansl
> Priority: Minor
> Attachments: 6427-notReady.txt, 6427-v1.txt, 6427-v2.txt,
> 6427-v3.txt, 6427-v4.txt, 6427-v5.txt, 6427-v7.txt
>
>
> When implementing higher level stores on top of HBase it is necessary to
> allow dynamic control over how long KVs must be kept around.
> Semi-static config options for ColumnFamilies (# of version or TTL) is not
> sufficient.
> This can be done with a few additional coprocessor hooks, or by makeing
> Store.ScanInfo pluggable.
> Was:
> The simplest way to achieve this is to have a pluggable class to determine
> the smallestReadpoint for Region. That way outside code can control what KVs
> to retain.
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