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Posted to derby-dev@db.apache.org by "Harshvardhan Gupta (JIRA)" <ji...@apache.org> on 2017/07/22 11:46:01 UTC

[jira] [Updated] (DERBY-6938) Obtain cardinality estimates and true estimates for base tables as well as for intermediate results for queries involving multiple joins.

     [ https://issues.apache.org/jira/browse/DERBY-6938?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Harshvardhan Gupta updated DERBY-6938:
--------------------------------------
    Attachment: traceout.txt

Following my previous comment I am also attaching the sample optimizer trace of Query 1a of job dataset where Optimizer ignores the HASH Tables which it predicts will spill to disk.

trace output String - "Skipping access path due to excess memory usage, maximum is 1048576".

>  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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