[HIVE-9645] Constant folding case NULL equality

• 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 Vijayaraghavan
• Created: 10/Feb/15 22:47
• Updated: 17/Jun/15 18:40
• Resolved: 16/Apr/15 01:13

Description

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.

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

Issue Links

• is related to: HIVE-9644 Fold case & when udfs
• relates to: CALCITE-727 Constant folding involving CASE and NULL
• supercedes: HIVE-9015 Constant Folding optimizer doesn't handle expressions involving null
• links to: RB request