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Posted to issues@hbase.apache.org by "Alex Feinberg (JIRA)" <ji...@apache.org> on 2012/05/03 20:54:48 UTC
[jira] [Commented] (HBASE-5494) Introduce a zk hosted table-wide
read/write lock so only one table operation at a time
[ https://issues.apache.org/jira/browse/HBASE-5494?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13267681#comment-13267681 ]
Alex Feinberg commented on HBASE-5494:
--------------------------------------
This patch implements a ZK-hosted mutual exclusion lock (DistributedLock), and table level locks (TableLockManager), and ensures that all schema changing operations are serialized. Further work would be needed to add read-write locks to handle region splitting and merges.
> Introduce a zk hosted table-wide read/write lock so only one table operation at a time
> --------------------------------------------------------------------------------------
>
> Key: HBASE-5494
> URL: https://issues.apache.org/jira/browse/HBASE-5494
> Project: HBase
> Issue Type: Improvement
> Reporter: stack
> Attachments: D2997.3.patch
>
>
> I saw this facility over in the accumulo code base.
> Currently we just try to sort out the mess when splits come in during an online schema edit; somehow we figure we can figure all possible region transition combinations and make the right call.
> We could try and narrow the number of combinations by taking out a zk table lock when doing table operations.
> For example, on split or merge, we could take a read-only lock meaning the table can't be disabled while these are running.
> We could then take a write only lock if we want to ensure the table doesn't change while disabling or enabling process is happening.
> Shouldn't be too hard to add.
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