[jira] [Assigned] (FLINK-19780) FlinkRelMdDistinctRowCount#getDistinctRowCount(Calc) will always return 0 when number of rows are large

["godfrey he (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/FLINK-19780?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

godfrey he reassigned FLINK-19780:
----------------------------------

    Assignee: Caizhi Weng

> FlinkRelMdDistinctRowCount#getDistinctRowCount(Calc) will always return 0 when number of rows are large
> -------------------------------------------------------------------------------------------------------
>
>                 Key: FLINK-19780
>                 URL: https://issues.apache.org/jira/browse/FLINK-19780
>             Project: Flink
>          Issue Type: Bug
>          Components: Table SQL / Planner
>            Reporter: Caizhi Weng
>            Assignee: Caizhi Weng
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 1.12.0
>
>
> Due to CALCITE-4351 {{FlinkRelMdDistinctRowCount#getDistinctRowCount(Calc)}} will always return 0 when number of rows are large.
> What I would suggest is to introduce our own {{FlinkRelMdUtil#numDistinctVals}} to treat small and large inputs in different ways. For small inputs we use the more precise {{RelMdUtil#numDistinctVals}} and for large inputs we copy the old, approximated implementation of {{RelMdUtil#numDistinctVals}}.
> This is a temporary solution. When CALCITE-4351 is fixed we should revert this commit.



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