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From "Harshvardhan Gupta (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DERBY-6938) Obtain cardinality estimates and true estimates for base tables as well as for intermediate results for queries involving multiple joins.
Date Wed, 02 Aug 2017 09:20:00 GMT

    [ https://issues.apache.org/jira/browse/DERBY-6938?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16110605#comment-16110605
] 

Harshvardhan Gupta commented on DERBY-6938:
-------------------------------------------

Bryan,

I agree with your observations. For production of efficient query plans, Cardinality Estimates,
Cost estimation and Plan space are all inter dependent on each other. I am filing another
issue under DERBY-6949 to track the effort on modelling HASH join's spill behaviour. I will
also update cost modelling details under DERBY-6949 shortly after I had to take a detour analyzing
HASH Join's behaviour.

Thanks,
Vardhan

>  Obtain cardinality estimates and true estimates for base tables as well as for intermediate
results for queries involving multiple joins. 
> -------------------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: DERBY-6938
>                 URL: https://issues.apache.org/jira/browse/DERBY-6938
>             Project: Derby
>          Issue Type: Sub-task
>          Components: SQL
>            Reporter: Harshvardhan Gupta
>            Assignee: Harshvardhan Gupta
>         Attachments: explain.txt, traceout.txt
>
>




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