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From "Feng Honghua (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-10252) Don't write back to WAL/memstore when Increment amount is zero (mostly for query rather than update intention)
Date Mon, 30 Dec 2013 13:04:52 GMT

    [ https://issues.apache.org/jira/browse/HBASE-10252?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13858773#comment-13858773
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Feng Honghua commented on HBASE-10252:
--------------------------------------

additional words:
1. no production code to v0 patch;
2. unit-test verifies: a) original Increment semantic doesn't change; b) noWriteBack takes
effect when increment amount is 0 (either single or all)

ping [~apurtell] :-)

> Don't write back to WAL/memstore when Increment amount is zero (mostly for query rather
than update intention)
> --------------------------------------------------------------------------------------------------------------
>
>                 Key: HBASE-10252
>                 URL: https://issues.apache.org/jira/browse/HBASE-10252
>             Project: HBase
>          Issue Type: Improvement
>          Components: regionserver
>            Reporter: Feng Honghua
>            Assignee: Feng Honghua
>         Attachments: HBASE-10252-trunk-v0.patch, HBASE-10252-trunk-v1.patch
>
>
> When user calls Increment by providing amount=0, we don't write the original value to
WAL or memstore : adding 0 yields a 'new' value just with the same value as the original one.
> 1. user provides 0 amount for query rather than for update, this fix is ok; this intention
is the most possible case;
> 2. user provides 0 amount for an update, this fix is also ok : no need to touch back-end
value if that value isn't changed;
> 3. either case we both return correct value, and keep subsequent query results correct
: if the 0 amount Increment is the first update, the query is the same for retrieving a 0
value or retrieving nothing;



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