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Posted to dev@hive.apache.org by "Gopal V (JIRA)" <ji...@apache.org> on 2015/02/21 08:29:11 UTC

[jira] [Updated] (HIVE-9644) CASE comparison operator rotation optimization

     [ https://issues.apache.org/jira/browse/HIVE-9644?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Gopal V updated HIVE-9644:
--------------------------
    Summary: CASE comparison operator rotation optimization  (was: Constant folding case for CASE/WHEN)

> CASE comparison operator rotation optimization
> ----------------------------------------------
>
>                 Key: HIVE-9644
>                 URL: https://issues.apache.org/jira/browse/HIVE-9644
>             Project: Hive
>          Issue Type: Bug
>          Components: Logical Optimizer
>    Affects Versions: 1.2.0
>            Reporter: Gopal V
>
> Constant folding for queries don't kick in for some automatically generated query patterns which look like this.
> {code}
> hive> explain select count(1) from store_sales where (case ss_sold_date when '1998-01-01' then 1 else null end)=1;
> {code}
> This should get rewritten by pushing the equality into the case branches.
> {code}
> select count(1) from store_sales where (case ss_sold_date when '1998-01-01' then 1=1 else null=1 end);
> {code}
> Ending up with a simplified filter condition, resolving itself as 
> {code}
> select count(1) from store_sales where ss_sold_date= '1998-01-01' ;
> {code}



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