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From "Andrew Mashenkov (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (IGNITE-4106) SQL: parallelize sql queries over cache local partitions
Date Wed, 09 Nov 2016 12:13:58 GMT

    [ https://issues.apache.org/jira/browse/IGNITE-4106?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15650767#comment-15650767
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Andrew Mashenkov commented on IGNITE-4106:
------------------------------------------

It seems that 
Every query thread read full node index and then filter data within its own partition subset.
Thus, query splitted to several threads will induce full node index to be read once per partition
subset.
In current (1 thread per node) approach, all query threads  work with its own smaller index.


> SQL: parallelize sql queries over cache local partitions
> --------------------------------------------------------
>
>                 Key: IGNITE-4106
>                 URL: https://issues.apache.org/jira/browse/IGNITE-4106
>             Project: Ignite
>          Issue Type: Improvement
>          Components: SQL
>    Affects Versions: 1.6, 1.7
>            Reporter: Andrew Mashenkov
>            Assignee: Andrew Mashenkov
>              Labels: performance
>         Attachments: 1node-4thread.jfr, 4node-1thread.jfr
>
>
> If we run SQL query on cache partitioned over several cluster nodes, it will be split
into several queries running in parallel. But really we will have one thread per query on
each node.
> So, for now, to improve SQL query performance we need to run more Ignite instances or
split caches manually.
> It seems to be better to split local SQL queries over cache partitions, so we would be
able to parallelize SQL query on every single node and utilize CPU more efficiently.



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