Details
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Improvement
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Status: Closed
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Major
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Resolution: Fixed
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4.0.0
Description
The query
create table ccn_table(key int, value string); set hive.cbo.enable=false; select * from ccn_table where key > '123a' ;
will scan all records(partitions) compared to older version, as the plan tells:
STAGE PLANS:
Stage: Stage-0
Fetch Operator
limit: -1
Processor Tree:
TableScan
alias: ccn_table
filterExpr: (key > '123a') (type: boolean)
Statistics: Num rows: 2 Data size: 180 Basic stats: COMPLETE Column stats: COMPLETE
GatherStats: false
Filter Operator
isSamplingPred: false
predicate: (key > '123a') (type: boolean)
Statistics: Num rows: 1 Data size: 90 Basic stats: COMPLETE Column stats: COMPLETE
Select Operator
expressions: key (type: int), value (type: string)
outputColumnNames: _col0, _col1
Statistics: Num rows: 1 Data size: 90 Basic stats: COMPLETE Column stats: COMPLETE
ListSink
When the TypeCheckProcFactory#getXpathOrFuncExprNodeDesc validates the expr: key > '123a', the operator(>) is not an equal operator(=), so the factory returns key > '123a' as it is. However all the subclass of GenericUDFBaseCompare(except GenericUDFOPEqualNS and GenericUDFOPNotEqualNS) would return null if either side of the function children is null, so it's safe to return constant null when processing the expr `key > '123a'`. This will benifit some queries when the cbo is disabled.
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