[PIG-1798] nested foreach - alias for expression does not work

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 0.8.0
• Assignee: Daniel Dai
• Reporter: Thejas Nair
• Created: 11/Jan/11 21:02
• Updated: 13/Nov/15 05:13

Description

In following example, the nested foreach statement has an alias ld used for output of distinct udf . Pig gives an error during query plan generation -

grunt> l = load 'x' as (a, b);
grunt> g = group l by a;
grunt> f = foreach g { ld = org.apache.pig.builtin.Distinct(l); f = filter ld by $0 > 1; generate COUNT(f);}
grunt> explain f;
2011-01-11 12:18:33,908 [main] WARN  org.apache.pig.PigServer - Encountered Warning IMPLICIT_CAST_TO_INT 1 time(s).
2011-01-11 12:18:33,908 [main] INFO  org.apache.pig.backend.hadoop.executionengine.HExecutionEngine - pig.usenewlogicalplan is set to true. New logical plan will be used.
2011-01-11 12:18:33,941 [main] ERROR org.apache.pig.tools.grunt.Grunt - ERROR 1067: Unable to explain alias f
Details at logfile: /Users/tejas/pig_comb2/trunk/pig_1294777094048.log



less /Users/tejas/pig_comb2/trunk/pig_1294777094048.log
Pig Stack Trace
---------------
ERROR 1067: Unable to explain alias f

org.apache.pig.impl.logicalLayer.FrontendException: ERROR 1067: Unable to explain alias f
        at org.apache.pig.PigServer.explain(PigServer.java:1053)
        at org.apache.pig.tools.grunt.GruntParser.explainCurrentBatch(GruntParser.java:358)
        at org.apache.pig.tools.grunt.GruntParser.processExplain(GruntParser.java:290)
        at org.apache.pig.tools.grunt.GruntParser.processExplain(GruntParser.java:253)
        at org.apache.pig.tools.pigscript.parser.PigScriptParser.Explain(PigScriptParser.java:665)
        at org.apache.pig.tools.pigscript.parser.PigScriptParser.parse(PigScriptParser.java:325)
        at org.apache.pig.tools.grunt.GruntParser.parseStopOnError(GruntParser.java:166)
        at org.apache.pig.tools.grunt.GruntParser.parseStopOnError(GruntParser.java:142)
        at org.apache.pig.tools.grunt.Grunt.run(Grunt.java:76)
        at org.apache.pig.Main.run(Main.java:475)
        at org.apache.pig.Main.main(Main.java:109)
Caused by: java.lang.NullPointerException
        at org.apache.pig.newplan.logical.ForeachInnerPlanVisitor.translateInnerPlanConnection(ForeachInnerPlanVisitor.java:87)
        at org.apache.pig.newplan.logical.ForeachInnerPlanVisitor.visit(ForeachInnerPlanVisitor.java:245)
        at org.apache.pig.impl.logicalLayer.LOFilter.visit(LOFilter.java:114)
        at org.apache.pig.impl.logicalLayer.LogicalOperator.visit(LogicalOperator.java:1)
        at org.apache.pig.impl.plan.DependencyOrderWalkerWOSeenChk.walk(DependencyOrderWalkerWOSeenChk.java:71)
        at org.apache.pig.impl.plan.PlanVisitor.visit(PlanVisitor.java:51)
        at org.apache.pig.newplan.logical.LogicalPlanMigrationVistor.visit(LogicalPlanMigrationVistor.java:245)
        at org.apache.pig.impl.logicalLayer.LOForEach.visit(LOForEach.java:132)
        at org.apache.pig.impl.logicalLayer.LogicalOperator.visit(LogicalOperator.java:1)
        at org.apache.pig.impl.plan.DependencyOrderWalker.walk(DependencyOrderWalker.java:70)
        at org.apache.pig.impl.plan.PlanVisitor.visit(PlanVisitor.java:51)
        at org.apache.pig.backend.hadoop.executionengine.HExecutionEngine.compile(HExecutionEngine.java:264)
        at org.apache.pig.PigServer.compilePp(PigServer.java:1460)
        at org.apache.pig.PigServer.explain(PigServer.java:1022)
        ... 10 more
================================================================================

Issue Links

• is duplicated by: PIG-1858 UDF in nested plan results frontend exception