[PIG-1732] New logical plan: logical plan get confused if we generate the same field twice in ForEach

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.8.0
• Fix Version/s: 0.8.0
• Component/s: impl
• Hadoop Flags: Reviewed
• Assignee: Daniel Dai
• Reporter: Daniel Dai
• Created: 17/Nov/10 00:32
• Updated: 17/Dec/10 22:46
• Resolved: 21/Nov/10 08:55

Description

The following script fail:

a = load '1.txt' as (a0, a1);
b = load '2.txt' as (b0, b1, b2);
c = foreach a generate a0, a1, a1 as a2;
d = union b, c;
e = foreach d generate $1;
explain e;

Error message:
ERROR 2000: Error processing rule ColumnMapKeyPrune. Try -t ColumnMapKeyPrune

org.apache.pig.impl.logicalLayer.FrontendException: ERROR 1067: Unable to explain alias e
at org.apache.pig.PigServer.explain(PigServer.java:958)
at org.apache.pig.tools.grunt.GruntParser.explainCurrentBatch(GruntParser.java:353)
at org.apache.pig.tools.grunt.GruntParser.processExplain(GruntParser.java:285)
at org.apache.pig.tools.grunt.GruntParser.processExplain(GruntParser.java:248)
at org.apache.pig.tools.pigscript.parser.PigScriptParser.Explain(PigScriptParser.java:605)
at org.apache.pig.tools.pigscript.parser.PigScriptParser.parse(PigScriptParser.java:327)
at org.apache.pig.tools.grunt.GruntParser.parseStopOnError(GruntParser.java:165)
at org.apache.pig.tools.grunt.GruntParser.parseStopOnError(GruntParser.java:141)
at org.apache.pig.tools.grunt.Grunt.exec(Grunt.java:90)
at org.apache.pig.Main.run(Main.java:498)
at org.apache.pig.Main.main(Main.java:107)
Caused by: org.apache.pig.impl.logicalLayer.FrontendException: ERROR 2042: Error in new logical plan. Try -Dpig.usenewlogicalplan=false.
at org.apache.pig.backend.hadoop.executionengine.HExecutionEngine.compile(HExecutionEngine.java:309)
at org.apache.pig.PigServer.compilePp(PigServer.java:1354)
at org.apache.pig.PigServer.explain(PigServer.java:927)
... 10 more
Caused by: org.apache.pig.impl.logicalLayer.FrontendException: ERROR 2000: Error processing rule ColumnMapKeyPrune. Try -t ColumnMapKeyPrune
at org.apache.pig.newplan.optimizer.PlanOptimizer.optimize(PlanOptimizer.java:120)
at org.apache.pig.backend.hadoop.executionengine.HExecutionEngine.compile(HExecutionEngine.java:277)
... 12 more
Caused by: java.lang.NullPointerException
at org.apache.pig.newplan.logical.relational.LOUnion.getSchema(LOUnion.java:75)
at org.apache.pig.newplan.logical.optimizer.SchemaResetter.visit(SchemaResetter.java:127)
at org.apache.pig.newplan.logical.relational.LOUnion.accept(LOUnion.java:102)
at org.apache.pig.newplan.DependencyOrderWalker.walk(DependencyOrderWalker.java:75)
at org.apache.pig.newplan.PlanVisitor.visit(PlanVisitor.java:50)
at org.apache.pig.newplan.logical.optimizer.SchemaPatcher.transformed(SchemaPatcher.java:43)
at org.apache.pig.newplan.optimizer.PlanOptimizer.optimize(PlanOptimizer.java:112)

The problem is caused by c = foreach a generate a0, a1, a1 as a2, in which we will generate two fields share one uid.