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From "pengcheng xiong" <pxi...@hortonworks.com>
Subject Re: Review Request 27415: CBO: Column names are missing from join expression in Map join with CBO enabled
Date Tue, 11 Nov 2014 22:34:13 GMT

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This is an automatically generated e-mail. To reply, visit:
https://reviews.apache.org/r/27415/
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(Updated Nov. 11, 2014, 10:34 p.m.)


Review request for hive, Ashutosh Chauhan and Vikram Dixit Kumaraswamy.


Repository: hive-git


Description
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On Hive 14 when CBO is enabled the column names are missing from the join expression. Rather
than to use external names "key", "value", some internal names such as "_col0" or "_col1"
are used. For map join with more than two tables it is very hard to figure the actual join
order. In this patch, I am going to address this issue not only for join but also for all
the other operators. And it will also be addressed in not only CLI but also TEZ environment.


The basic idea to transform the internal name to external name is to
(1) use snapshotLogicalPlanForExplain() to make a snapshot of a logical plan after logical
optimization
(2) for each operator in the explain task, call the prepareCBOExplain function for each operatorDesc
(2.1) Each operator uses ''helpGetStartOp'' to map to a logical operator (start point) in
the LogicalPlan
(2.2) From start point, each operatorDesc uses ''findExternalName'' to track its external
name

And, an important assumption here is that, every physical operator (SEL, RS, JOIN (include
hashtablesinkop, join, mapjoinop, mergejoinop, semijoin), FIL, GRY, FS, UNION) that is included
in the explain can find its corresponding logical operator. If it is not found, its internal
column names will be used.


Diffs (updated)
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  common/src/java/org/apache/hadoop/hive/conf/HiveConf.java cca57d2 
  ql/src/java/org/apache/hadoop/hive/ql/exec/ExplainTask.java 8e1ba48 
  ql/src/java/org/apache/hadoop/hive/ql/optimizer/AbstractSMBJoinProc.java c9e8086 
  ql/src/java/org/apache/hadoop/hive/ql/optimizer/ConvertJoinMapJoin.java 04bafda 
  ql/src/java/org/apache/hadoop/hive/ql/optimizer/MapJoinProcessor.java 2d82cd8 
  ql/src/java/org/apache/hadoop/hive/ql/optimizer/physical/CommonJoinTaskDispatcher.java 3df1c26

  ql/src/java/org/apache/hadoop/hive/ql/optimizer/physical/LocalMapJoinProcFactory.java 9076d48

  ql/src/java/org/apache/hadoop/hive/ql/optimizer/physical/Vectorizer.java 2c02bd4 
  ql/src/java/org/apache/hadoop/hive/ql/parse/ExplainColumnContext.java PRE-CREATION 
  ql/src/java/org/apache/hadoop/hive/ql/parse/ParseContext.java 8215c26 
  ql/src/java/org/apache/hadoop/hive/ql/parse/SemanticAnalyzer.java 88fd0fc 
  ql/src/java/org/apache/hadoop/hive/ql/parse/TaskCompiler.java 23fbbe1 
  ql/src/java/org/apache/hadoop/hive/ql/plan/AbstractOperatorDesc.java 8410664 
  ql/src/java/org/apache/hadoop/hive/ql/plan/FileSinkDesc.java 8b25c2b 
  ql/src/java/org/apache/hadoop/hive/ql/plan/FilterDesc.java 5856743 
  ql/src/java/org/apache/hadoop/hive/ql/plan/GroupByDesc.java 7a0b0da 
  ql/src/java/org/apache/hadoop/hive/ql/plan/HashTableSinkDesc.java 1e0eb6b 
  ql/src/java/org/apache/hadoop/hive/ql/plan/JoinDesc.java 0e2c6ee 
  ql/src/java/org/apache/hadoop/hive/ql/plan/MapJoinDesc.java d43bd60 
  ql/src/java/org/apache/hadoop/hive/ql/plan/OperatorDesc.java c8c9570 
  ql/src/java/org/apache/hadoop/hive/ql/plan/ReduceSinkDesc.java 57beb69 
  ql/src/java/org/apache/hadoop/hive/ql/plan/SelectDesc.java fa6b548 
  ql/src/test/queries/clientpositive/explainColTest_1.q PRE-CREATION 
  ql/src/test/queries/clientpositive/explainColTest_2.q PRE-CREATION 
  ql/src/test/results/clientpositive/explainColTest_1.q.out PRE-CREATION 
  ql/src/test/results/clientpositive/explainColTest_2.q.out PRE-CREATION 
  ql/src/test/results/clientpositive/tez/explainColTest_1.q.out PRE-CREATION 
  ql/src/test/results/clientpositive/tez/explainColTest_2.q.out PRE-CREATION 

Diff: https://reviews.apache.org/r/27415/diff/


Testing
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Thanks,

pengcheng xiong


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