[jira] [Assigned] (HIVE-24373) Wrong predicate is pushed down for view with constant value projection.

["mahesh kumar behera (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HIVE-24373?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

mahesh kumar behera reassigned HIVE-24373:
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> Wrong predicate is pushed down for view with constant value projection.
> -----------------------------------------------------------------------
>
>                 Key: HIVE-24373
>                 URL: https://issues.apache.org/jira/browse/HIVE-24373
>             Project: Hive
>          Issue Type: Bug
>            Reporter: mahesh kumar behera
>            Assignee: mahesh kumar behera
>            Priority: Major
>
> For below query the predicate pushed down for one of the table scan is not proper.
>  
> {code:java}
> set hive.explain.user=false;
> set hive.cbo.enable=false;
> set hive.optimize.ppd=true;DROP TABLE arc;
> CREATE table arc(`dt_from` string, `dt_to` string);
> CREATE table loc1(`dt_from` string, `dt_to` string);
> CREATE
>  VIEW view AS
>      SELECT
>         '9999' as DT_FROM,
>         uuid() as DT_TO
>      FROM
>        loc1
>  UNION ALL
>      SELECT
>         dt_from as DT_FROM,
>         uuid() as DT_TO
>      FROM
>        arc;
> EXPLAIN
>     SELECT
>       dt_from, dt_to
>     FROM
>       view
>     WHERE
>       '2020'  between dt_from and dt_to;
> {code}
>  
> For table loc1,  DT_FROM is projected as '9999' so the predicate "predicate: '2020' BETWEEN '9999' AND _col1 (type: boolean)" is proper. But for table arc, the column is projected so the predicate should be "predicate: '2020' BETWEEN _col0 (type: boolean) AND _col1 (type: boolean)".
> This is because the predicates are stored in a map for each expression. Here the expression is "_col0". When the predicate is pushed down the union, the same predicate is used for creating the filter expression. Later when constant replacement is done, the first filter is overwriting the second one.
> So we should create a clone (as done at other places) before using the cached predicate for filter. This way the overwrite can be avoided.   
>  



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