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From "Prasanth Jayachandran (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-11477) CBO inserts a UDF cast for integer type promotion (only for negative numbers)
Date Thu, 06 Aug 2015 21:37:04 GMT

     [ https://issues.apache.org/jira/browse/HIVE-11477?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

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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