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Posted to derby-dev@db.apache.org by "Mike Matrigali (JIRA)" <ji...@apache.org> on 2016/02/21 19:52:18 UTC

[jira] [Commented] (DERBY-6873) handle btree rebalance case when it can't get table level lock.

    [ https://issues.apache.org/jira/browse/DERBY-6873?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15156161#comment-15156161 ] 

Mike Matrigali commented on DERBY-6873:
---------------------------------------

elegant solution would be to do the operation without a table lock.  This is difficult to do with concurrent inserts, deletes, splits, merges, ...

> handle btree rebalance case when it can't get table level lock.
> ---------------------------------------------------------------
>
>                 Key: DERBY-6873
>                 URL: https://issues.apache.org/jira/browse/DERBY-6873
>             Project: Derby
>          Issue Type: Improvement
>            Reporter: Mike Matrigali
>
> current implementation of btree requires table level lock on index to rebalance.  This can result in inefficient tree structure if lock can not
> be obtained and if post commit retry also fails.  Similar to other problems
> if post commit retry does not succeed.
> May also leave unreclaimed space that could be reclaimed.
> Work around is to run compress on the table in offline mode.



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