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https://issues.apache.org/jira/browse/HBASE-4583?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13144580#comment-13144580
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Lars Hofhansl commented on HBASE-4583:
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I don't think that HBASE-2856 will address the issues I raised above (which is
caused by deleting KVs from the memstore).
Updating the WAL first, then applying the changes to the memstore, and making
them visible immediately, all while holding the rowlock is a relatively little
change. It'll make Increment/Append/ICV behave correctly in the face of failing
WAL sync's, but will also significantly slow them down (in terms of throughput,
but not latency).
I will factor some common bits out (similar to my initial patch), so that if we
want to tackle this in the future (for example by maintaining the lowest
current readpoint in use, or something), there'll be just one place to change
it.
If one want performance, one would set writeToWal to false; but maybe these
three ops should get another flag to allow for delayed log flush (which would
be the current behavior).
Lastly, we can just document that the Append and Increment operations are
convenience methods for grouping many updates into a single roundtrip (not to
achieve consistency between CFs).
> Integrate RWCC with Append and Increment operations
> ---------------------------------------------------
>
> Key: HBASE-4583
> URL: https://issues.apache.org/jira/browse/HBASE-4583
> Project: HBase
> Issue Type: Bug
> Reporter: Lars Hofhansl
> Assignee: Lars Hofhansl
> Fix For: 0.94.0
>
> Attachments: 4583-v2.txt, 4583-v3.txt, 4583-v4.txt, 4583.txt
>
>
> Currently Increment and Append operations do not work with RWCC and hence a
> client could see the results of multiple such operation mixed in the same
> Get/Scan.
> The semantics might be a bit more interesting here as upsert adds and removes
> to and from the memstore.
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