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Posted to derby-dev@db.apache.org by "Harshvardhan Gupta (JIRA)" <ji...@apache.org> on 2017/06/18 13:54:00 UTC
[jira] [Comment Edited] (DERBY-6940) Enhance derby statistics for
more accurate selectivity estimates.
[ https://issues.apache.org/jira/browse/DERBY-6940?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16053201#comment-16053201 ]
Harshvardhan Gupta edited comment on DERBY-6940 at 6/18/17 1:53 PM:
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Additionally we need to work on upgrade procedures, while trying to access statistics info of an index created before this patch, Derby will throw a NPE due to absence of the new statistics in those indexes.
was (Author: harshvardhan145):
Additionally we need to work on upgrade procedures, while trying to access statistics info of an index created before this patch, Derby will throw a NPE due to absence of the new statistics.
> Enhance derby statistics for more accurate selectivity estimates.
> -----------------------------------------------------------------
>
> Key: DERBY-6940
> URL: https://issues.apache.org/jira/browse/DERBY-6940
> Project: Derby
> Issue Type: Sub-task
> Components: SQL
> Reporter: Harshvardhan Gupta
> Assignee: Harshvardhan Gupta
> Priority: Minor
> Attachments: derby-6940.diff
>
>
> Derby should collect extra statistics during index build time, statistics refresh time which will help optimizer make more precise selectivity estimates and chose better execution paths.
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