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From "Gopal V (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-10716) Fold case/when udf for expression involving nulls in filter operator.
Date Wed, 27 May 2015 04:47:18 GMT

    [ https://issues.apache.org/jira/browse/HIVE-10716?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14560400#comment-14560400
] 

Gopal V commented on HIVE-10716:
--------------------------------

[~ashutoshc]: LGTM - +1 for the count(1) case, but it looks really odd that the {{TableScan::filterExpr}}
is not getting folded for this.

TableScan FilterExpr is populated before this folding happens, so it might just be an optimization
ordering issue?

{code}
hive> explain select count(1) from store_sales where (case ss_sold_date when 'x' then 1
else null end)=1;

STAGE PLANS:
  Stage: Stage-1
    Tez
      Edges:
        Reducer 2 <- Map 1 (SIMPLE_EDGE)
      DagName: gopal_20150526214205_80c41d84-1694-47e9-ab24-144f8007b187:13
      Vertices:
        Map 1 
            Map Operator Tree:
                TableScan
                  alias: store_sales
                  filterExpr: CASE (ss_sold_date) WHEN ('x') THEN (true) ELSE (null) END (type:
int)
                  Statistics: Num rows: 1 Data size: 0 Basic stats: PARTIAL Column stats:
COMPLETE
                  Filter Operator
                    predicate: (ss_sold_date = 'x') (type: boolean)
                    Statistics: Num rows: 1 Data size: 0 Basic stats: PARTIAL Column stats:
COMPLETE
                    Select Operator
                      Statistics: Num rows: 1 Data size: 0 Basic stats: PARTIAL Column stats:
COMPLETE
                      Group By Operator
                        aggregations: count(1)
                        mode: hash
                        outputColumnNames: _col0
                        Statistics: Num rows: 1 Data size: 93 Basic stats: COMPLETE Column
stats: COMPLETE
                        Reduce Output Operator
                          sort order: 
                          Statistics: Num rows: 1 Data size: 93 Basic stats: COMPLETE Column
stats: COMPLETE
                          value expressions: _col0 (type: bigint)
            Execution mode: vectorized
        Reducer 2 
            Reduce Operator Tree:
              Group By Operator
                aggregations: count(VALUE._col0)
{code}

> Fold case/when udf for expression involving nulls in filter operator.
> ---------------------------------------------------------------------
>
>                 Key: HIVE-10716
>                 URL: https://issues.apache.org/jira/browse/HIVE-10716
>             Project: Hive
>          Issue Type: New Feature
>          Components: Logical Optimizer
>    Affects Versions: 1.3.0
>            Reporter: Ashutosh Chauhan
>            Assignee: Ashutosh Chauhan
>         Attachments: HIVE-10716.patch
>
>
> From HIVE-10636 comments, more folding is possible.



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