[jira] [Assigned] (IGNITE-18206) Sql. Prohibit using of DISTINCT|SORTED 2-phase aggregates

["Evgeny Stanilovsky (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/IGNITE-18206?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Evgeny Stanilovsky reassigned IGNITE-18206:
-------------------------------------------

    Affects Version/s: 3.0.0-beta1
             Assignee: Evgeny Stanilovsky

> Sql. Prohibit using of DISTINCT|SORTED 2-phase aggregates
> ---------------------------------------------------------
>
>                 Key: IGNITE-18206
>                 URL: https://issues.apache.org/jira/browse/IGNITE-18206
>             Project: Ignite
>          Issue Type: Improvement
>          Components: sql
>    Affects Versions: 3.0.0-beta1
>            Reporter: Konstantin Orlov
>            Assignee: Evgeny Stanilovsky
>            Priority: Major
>              Labels: ignite-3
>
> Currently, 2-phase aggregate is used even for aggregates with DISTINCT and/or ORDER BY clauses. This is possible because of unnatural resulting row produced by a MAP aggregate: in a single column it accumulates all rows belonging to a particular group.
> Such an approach causes errors in cost calculation, as well as closes the door for further optimizations, like reusing BinaryTuple for sql row, because of a complex structure of the row.
> As a first step, let's prohibit using of 2-phase aggregates for cases where collection of rows for particular row should be preserved in order to compute the final result (DISTINCT|SORTED aggregates).



--
This message was sent by Atlassian Jira
(v8.20.10#820010)