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From "Gopal V (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-9645) Constant folding case NULL equality
Date Sat, 25 Apr 2015 09:06:38 GMT

    [ https://issues.apache.org/jira/browse/HIVE-9645?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14512357#comment-14512357
] 

Gopal V commented on HIVE-9645:
-------------------------------

[~apivovarov]: the whole VOID handling cases where only done partly since the newest patch
generates ((int)null) instead of void(null) for column types.

> Constant folding case NULL equality
> -----------------------------------
>
>                 Key: HIVE-9645
>                 URL: https://issues.apache.org/jira/browse/HIVE-9645
>             Project: Hive
>          Issue Type: Bug
>          Components: Logical Optimizer
>    Affects Versions: 0.14.0, 1.0.0, 1.1.0
>            Reporter: Gopal V
>            Assignee: Ashutosh Chauhan
>             Fix For: 1.2.0
>
>         Attachments: HIVE-9645.1.patch, HIVE-9645.2.patch, HIVE-9645.3.patch, HIVE-9645.4.patch,
HIVE-9645.5.patch, HIVE-9645.6.patch, HIVE-9645.7.patch, HIVE-9645.patch
>
>
> Hive logical optimizer does not follow the Null scan codepath when encountering a NULL
= 1;
> NULL = 1 is not evaluated as false in the constant propogation implementation.
> {code}
> hive> explain select count(1) from store_sales where null=1;
> ...
>              TableScan
>                   alias: store_sales
>                   filterExpr: (null = 1) (type: boolean)
>                   Statistics: Num rows: 550076554 Data size: 49570324480 Basic stats:
COMPLETE Column stats: COMPLETE
>                   Filter Operator
>                     predicate: (null = 1) (type: boolean)
>                     Statistics: Num rows: 275038277 Data size: 0 Basic stats: PARTIAL
Column stats: COMPLETE
> {code}



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