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https://issues.apache.org/jira/browse/HIVE-11477?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Prasanth Jayachandran updated HIVE-11477:
-----------------------------------------
Priority: Critical (was: Major)
> CBO inserts a UDF cast for integer type promotion (only for negative numbers)
> -----------------------------------------------------------------------------
>
> 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
> Priority: Critical
>
> 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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