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Posted to issues@impala.apache.org by "Tim Armstrong (Jira)" <ji...@apache.org> on 2021/01/25 19:01:00 UTC

[jira] [Resolved] (IMPALA-10229) Analytic limit pushdown optimization can be applied incorrectly based on predicates present

     [ https://issues.apache.org/jira/browse/IMPALA-10229?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Tim Armstrong resolved IMPALA-10229.
------------------------------------
    Fix Version/s: Impala 4.0
       Resolution: Fixed

Finished both subtasks

> Analytic limit pushdown optimization can be applied incorrectly based on predicates present
> -------------------------------------------------------------------------------------------
>
>                 Key: IMPALA-10229
>                 URL: https://issues.apache.org/jira/browse/IMPALA-10229
>             Project: IMPALA
>          Issue Type: Bug
>          Components: Frontend
>            Reporter: Tim Armstrong
>            Assignee: Tim Armstrong
>            Priority: Blocker
>              Labels: correctness
>             Fix For: Impala 4.0
>
>
> {noformat}
> [localhost.EXAMPLE.COM:21050] default> select * from (select month, id, rank() over (partition by month order by id desc) rnk from functional_parquet.alltypes WHERE month >= 11) v order by month, id limit 3;
> +-------+------+-----+
> | month | id   | rnk |
> +-------+------+-----+
> | 11    | 6987 | 3   |
> | 11    | 6988 | 2   |
> | 11    | 6989 | 1   |
> +-------+------+-----+
> Fetched 3 row(s) in 4.16s
> {noformat}
> These are not the top 3 rows when ordering by month, id . Hive's result is correct:
> {noformat}
> +----------+-------+--------+
> | v.month  | v.id  | v.rnk  |
> +----------+-------+--------+
> | 11       | 3040  | 600    |
> | 11       | 3041  | 599    |
> | 11       | 3042  | 598    |
> +----------+-------+--------+
> {noformat}
> I think when there's no select predicates, that the ordering in the analytic sort needs to exactly match the TOP N sort ordering. I'm not sure if there are fixes needed for the case where there are select predicates.



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