[
https://issues.apache.org/jira/browse/HBASE-12751?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14639243#comment-14639243
]
Elliott Clark commented on HBASE-12751:
---------------------------------------
bq.Let me look at the patch again. The above description sounds like how it
mostly worked previous. Let me see.... Thanks E.
Yeah it's pretty similar. The patch is just adding to the wal append/sync queue
earlier. That allows a creating the sequence id/mvcc number for real. Because
the edits are already in the queue for the wal we know for sure that their
ordering is the same as the sequence number.
The bonus nice thing from this re-ordering is that adding to the memstore and
the append are running in parallel.
> 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-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.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
