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From "Harshvardhan Gupta (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DERBY-6942) Utilise additional statistics for selectivity estimates.
Date Sat, 01 Jul 2017 21:19:00 GMT

    [ https://issues.apache.org/jira/browse/DERBY-6942?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16071405#comment-16071405
] 

Harshvardhan Gupta commented on DERBY-6942:
-------------------------------------------

Let me emphasize on this improvement in case of multiple joins: Although in the above example
my changes didn't change the cost (it shouldn't since during execution by that conglomerate
needs to do the same work), improvement in cardinality estimates will help us avoid cascading
errors during cost estimation of joins.

> Utilise additional statistics for selectivity estimates.
> --------------------------------------------------------
>
>                 Key: DERBY-6942
>                 URL: https://issues.apache.org/jira/browse/DERBY-6942
>             Project: Derby
>          Issue Type: Sub-task
>          Components: SQL
>            Reporter: Harshvardhan Gupta
>            Assignee: Harshvardhan Gupta
>            Priority: Minor
>         Attachments: DERBY-6942.diff, z12.txt, z13.txt
>
>




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