[jira] [Updated] (IGNITE-8596) SQL: remove unnecessary index lookups when query parallelism is enabled

["Maxim Muzafarov (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/IGNITE-8596?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Maxim Muzafarov updated IGNITE-8596:
------------------------------------
    Fix Version/s:     (was: 2.8)
                   2.9

> SQL: remove unnecessary index lookups when query parallelism is enabled
> -----------------------------------------------------------------------
>
>                 Key: IGNITE-8596
>                 URL: https://issues.apache.org/jira/browse/IGNITE-8596
>             Project: Ignite
>          Issue Type: Improvement
>          Components: sql
>    Affects Versions: 2.5
>            Reporter: Vladimir Ozerov
>            Priority: Major
>              Labels: performance
>             Fix For: 2.9
>
>
> See {{org.apache.ignite.internal.processors.query.h2.twostep.GridMapQueryExecutor#onQueryRequest}} method. If table is segmented, we will submit as many SQL requests as much segments. But consider a case when target cache partition(s) is already defined by user or derived through partition pruning. In this case most of segments will not contain useful information and return empty result set. At the same time these queries may impose index or data page scans, thus consuming resources without a reason.
> To mitigate the problem we should not submit SQL requests to segments we are not interested in.
> Note that it is not sufficient to simply skip SQL requests on mapper, because reducer expects separate response for every message. We should fix both local mapper logic as well as protocol.



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