[jira] [Resolved] (IMPALA-15189) HBO for computing SortNode cardinality

["Quanlong Huang (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/IMPALA-15189?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Quanlong Huang resolved IMPALA-15189.
-------------------------------------
    Fix Version/s: Impala 5.0.0
       Resolution: Fixed

> HBO for computing SortNode cardinality
> --------------------------------------
>
>                 Key: IMPALA-15189
>                 URL: https://issues.apache.org/jira/browse/IMPALA-15189
>             Project: IMPALA
>          Issue Type: New Feature
>            Reporter: Quanlong Huang
>            Assignee: Quanlong Huang
>            Priority: Major
>             Fix For: Impala 5.0.0
>
>
> A sort only reorders rows, so its output row count equals its child's *unless* it applies a limit: TopN, Partitioned TopN, or a total sort carrying a LIMIT.
> For instance, the SortNode created for the following analytic function is a Partitioned TopN:
> {code:sql}
> select ..., rank() over (partition by a order by b) rnk ... where rnk < 5"{code}
> Its output cardinality depends on the distinct number of column a and the per-partition limit 5.
> HBO should track cardinality for SortNodes when they are not cardinality-preserving.



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