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Posted to issues@drill.apache.org by "Boaz Ben-Zvi (JIRA)" <ji...@apache.org> on 2019/02/26 02:17:00 UTC

[jira] [Updated] (DRILL-4667) Improve memory footprint of broadcast joins

     [ https://issues.apache.org/jira/browse/DRILL-4667?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Boaz Ben-Zvi updated DRILL-4667:
--------------------------------
    Fix Version/s:     (was: 1.16.0)
                   1.17.0

> Improve memory footprint of broadcast joins
> -------------------------------------------
>
>                 Key: DRILL-4667
>                 URL: https://issues.apache.org/jira/browse/DRILL-4667
>             Project: Apache Drill
>          Issue Type: Improvement
>          Components: Execution - Relational Operators
>    Affects Versions: 1.6.0
>            Reporter: Aman Sinha
>            Assignee: Boaz Ben-Zvi
>            Priority: Major
>             Fix For: 1.17.0
>
>
> For broadcast joins, currently Drill optimizes the data transfer across the network for broadcast table by sending a single copy to the receiving node which then distributes it to all minor fragments running on that particular node.  However, each minor fragment builds its own hash table (for a hash join) using this broadcast table.  We can substantially improve the memory footprint by having a shared copy of the hash table among multiple minor fragments on a node.  



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