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https://issues.apache.org/jira/browse/DERBY-6940?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16056415#comment-16056415
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Bryan Pendleton commented on DERBY-6940:
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It seems like you are making very good progress on this!
I wonder: if you follow the code paths for SYSCOLUMNS.COLUMNDEFAULT, will that
give you some examples of how to store the min/max values in the statistics?
Also, I wonder if you could perhaps update the description of this job to
provide some more background about the overall intent of the new statistics. It
would be useful to have some (very high level) descriptions of how we would use
these new statistics during query planning.
And, do you think this is a complete list of the additional statistics that it
would be useful to have? For example, is it worth comparing the Derby-collected
statistics with the statistics used by, say, Postgres, to see if there are any
other interesting statistics we could be collecting at this time?
> 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_2.diff, 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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