[jira] [Assigned] (IGNITE-21948) Rethink distributed aggregates converter rules.

["Andrey Mashenkov (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/IGNITE-21948?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Andrey Mashenkov reassigned IGNITE-21948:
-----------------------------------------

    Assignee: Andrey Mashenkov

> Rethink distributed aggregates converter rules.
> -----------------------------------------------
>
>                 Key: IGNITE-21948
>                 URL: https://issues.apache.org/jira/browse/IGNITE-21948
>             Project: Ignite
>          Issue Type: Improvement
>          Components: sql
>            Reporter: Andrey Mashenkov
>            Assignee: Andrey Mashenkov
>            Priority: Major
>              Labels: ignite-3, perfomance, sql
>
> *Motivation.*
> We convert LogicalAggregate to map-reduce unconditionally (if possible), which blows plan search space.
> Some plans, which have reduce-phase followed by map-phase without Exchange, make no sense and will be thrown away after applying cost model (if no - there is a bug).
> *Suggestion.*
> What if we will emit only plans with colocated aggregates? 
> We can write rules to pushdown colocated aggregate through Exchange via splitting into map-reduce phases, if colocation can't be preserved.
> If Exchange can preserve colocation, then aggregate is pushed gown without splitting.
> Let's investigate, if we can eliminate (or significantly decrease number of plans)
>  # with Exchange-less Reduce->Map
>  # map-reduce aggregates on colocated data.



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