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https://issues.apache.org/jira/browse/HBASE-12751?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14641897#comment-14641897
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stack commented on HBASE-12751:
-------------------------------
bq. ...could we just add to MemStore in the WAL appender/ringbuffer consuming
thread...
Thinking on it more, the above won't do much for us. We'd be adding edits to
memstore making them available for reads before the sync completes. Add the
edits to an intermediate collection that gets added to memstore after syncs
complete (would only make sense if the collection were uncontended)?
> Allow RowLock to be reader writer
> ---------------------------------
>
> Key: HBASE-12751
> URL: https://issues.apache.org/jira/browse/HBASE-12751
> Project: HBase
> Issue Type: Bug
> Components: regionserver
> Affects Versions: 2.0.0, 1.3.0
> Reporter: Elliott Clark
> Assignee: Elliott Clark
> Fix For: 2.0.0, 1.3.0
>
> Attachments: HBASE-12751-v1.patch, HBASE-12751-v10.patch,
> HBASE-12751-v10.patch, HBASE-12751-v11.patch, HBASE-12751-v12.patch,
> HBASE-12751-v13.patch, HBASE-12751-v14.patch, HBASE-12751-v15.patch,
> HBASE-12751-v16.patch, HBASE-12751-v17.patch, HBASE-12751-v2.patch,
> HBASE-12751-v3.patch, HBASE-12751-v4.patch, HBASE-12751-v5.patch,
> HBASE-12751-v6.patch, HBASE-12751-v7.patch, HBASE-12751-v8.patch,
> HBASE-12751-v9.patch, HBASE-12751.patch
>
>
> Right now every write operation grabs a row lock. This is to prevent values
> from changing during a read modify write operation (increment or check and
> put). However it limits parallelism in several different scenarios.
> If there are several puts to the same row but different columns or stores
> then this is very limiting.
> If there are puts to the same column then mvcc number should ensure a
> consistent ordering. So locking is not needed.
> However locking for check and put or increment is still needed.
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