[HIVE-9644] Fold case & when udfs

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.14.0, 1.0.0, 1.1.0
• Fix Version/s: 1.2.0
• Component/s: Logical Optimizer
• Assignee: Ashutosh Chauhan
• Reporter: Gopal V
• Created: 10/Feb/15 22:45
• Updated: 23/Dec/15 00:38
• Resolved: 07/May/15 17:35

Description

Constant folding for queries don't kick in for some automatically generated query patterns which look like this.

hive> explain select count(1) from store_sales where (case ss_sold_date when '1998-01-01' then 1 else null end)=1;

This should get rewritten by pushing the equality into the case branches.

select count(1) from store_sales where (case ss_sold_date when '1998-01-01' then 1=1 else null=1 end);

Ending up with a simplified filter condition, resolving itself as

select count(1) from store_sales where ss_sold_date= '1998-01-01' ;

Issue Links

• is depended upon by: HIVE-10636 CASE comparison operator rotation optimization
• is related to: CALCITE-727 Constant folding involving CASE and NULL
• relates to: HIVE-9645 Constant folding case NULL equality
• relates to: HIVE-12735 Constant folding for WHEN/CASE expression does not set return type correctly
• relates to: HIVE-10716 Fold case/when udf for expression involving nulls in filter operator.
• links to: RB request