Prasanth Jayachandran created HIVE-11477:
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Summary: CBO inserts a UDF cast for integer type promotion
Key: HIVE-11477
URL: https://issues.apache.org/jira/browse/HIVE-11477
Project: Hive
Issue Type: Bug
Affects Versions: 2.0.0
Reporter: Prasanth Jayachandran
Assignee: Pengcheng Xiong
When CBO is enabled, filters which compares tinyint, smallint columns with
constant integer types will insert a UDFToInteger cast for the columns. When
CBO is disabled, there is no such UDF. This behaviour breaks ORC predicate
pushdown feature as ORC ignores UDFs in the filters.
In the following examples column t is tinyint
{code:title=Explain for select count(*) from orc_ppd where t < -127; (CBO OFF)}
Filter Operator [FIL_9]
predicate:(t = 125) (type: boolean)
Statistics:Num rows: 1050 Data size: 611757 Basic
stats: COMPLETE Column stats: NONE
TableScan [TS_0]
alias:orc_ppd
Statistics:Num rows: 2100 Data size: 1223514
Basic stats: COMPLETE Column stats: NONE
{code}
{code:title=Explain for select count(*) from orc_ppd where t < -127; (CBO ON)}
Filter Operator [FIL_10]
predicate:(UDFToInteger(t) < -127) (type: boolean)
Statistics:Num rows: 700 Data size: 407838 Basic
stats: COMPLETE Column stats: NONE
TableScan [TS_0]
alias:orc_ppd
Statistics:Num rows: 2100 Data size: 1223514
Basic stats: COMPLETE Column stats: NONE
{code}
CBO does not insert such cast for non-negative numbers
{code:title=Explain for select count(*) from orc_ppd where t < 127; (CBO ON)}
Filter Operator [FIL_10]
predicate:(t < 127) (type: boolean)
Statistics:Num rows: 700 Data size: 407838 Basic
stats: COMPLETE Column stats: NONE
TableScan [TS_0]
alias:orc_ppd
Statistics:Num rows: 2100 Data size: 1223514
Basic stats: COMPLETE Column stats: NONE
{code}
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