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Koji Noguchi commented on PIG-2968: ----------------------------------- Log showing {noformat} $ cat /Users/knoguchi/git/pig/pig_1350068049281.logPig Stack Trace --------------- ERROR 2000: Error processing rule ColumnMapKeyPrune. Try -t ColumnMapKeyPrune org.apache.pig.impl.logicalLayer.FrontendException: ERROR 1067: Unable to explain alias another at org.apache.pig.PigServer.explain(PigServer.java:999) at org.apache.pig.tools.grunt.GruntParser.explainCurrentBatch(GruntParser.java:398) at org.apache.pig.tools.grunt.GruntParser.processExplain(GruntParser.java:330) at org.apache.pig.tools.grunt.GruntParser.processExplain(GruntParser.java:293) at org.apache.pig.tools.pigscript.parser.PigScriptParser.Explain(PigScriptParser.java:715) at org.apache.pig.tools.pigscript.parser.PigScriptParser.parse(PigScriptParser.java:342) at org.apache.pig.tools.grunt.GruntParser.parseStopOnError(GruntParser.java:193) at org.apache.pig.tools.grunt.GruntParser.parseStopOnError(GruntParser.java:169) at org.apache.pig.tools.grunt.Grunt.exec(Grunt.java:84) at org.apache.pig.Main.run(Main.java:604) at org.apache.pig.Main.main(Main.java:154) 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:122) at org.apache.pig.backend.hadoop.executionengine.HExecutionEngine.compile(HExecutionEngine.java:277) at org.apache.pig.PigServer.compilePp(PigServer.java:1322) at org.apache.pig.PigServer.explain(PigServer.java:984) ... 10 more Caused by: java.util.ConcurrentModificationException at java.util.AbstractList$Itr.checkForComodification(AbstractList.java:372) at java.util.AbstractList$Itr.next(AbstractList.java:343) at org.apache.pig.newplan.logical.rules.ColumnPruneVisitor.removeSubTree(ColumnPruneVisitor.java:451) at org.apache.pig.newplan.logical.rules.ColumnPruneVisitor.removeSubTree(ColumnPruneVisitor.java:452) at org.apache.pig.newplan.logical.rules.ColumnPruneVisitor.visit(ColumnPruneVisitor.java:431) at org.apache.pig.newplan.logical.relational.LOForEach.accept(LOForEach.java:76) at org.apache.pig.newplan.ReverseDependencyOrderWalker.walk(ReverseDependencyOrderWalker.java:70) at org.apache.pig.newplan.PlanVisitor.visit(PlanVisitor.java:52) at org.apache.pig.newplan.logical.rules.ColumnMapKeyPrune$ColumnMapKeyPruneTransformer.transform(ColumnMapKeyPrune.java:141) at org.apache.pig.newplan.optimizer.PlanOptimizer.optimize(PlanOptimizer.java:110) ... 13 more ================================================================================ {noformat} > ColumnMapKeyPrune fails to prune a subtree inside foreach > --------------------------------------------------------- > > Key: PIG-2968 > URL: https://issues.apache.org/jira/browse/PIG-2968 > Project: Pig > Issue Type: Bug > Reporter: Koji Noguchi > Assignee: Koji Noguchi > Priority: Minor > > Sample code > {noformat} > $ cat test/foreach.pig > daily = load 'nyse' as (exchange, symbol); > grpd = group daily by exchange; > uniquecnt = foreach grpd { > sym = daily.symbol; > uniq_sym = distinct sym; > generate group, uniq_sym; > }; > another = FOREACH uniquecnt GENERATE group; > explain another; > {noformat} > This breaks when it tries to prune uniq_sym->sym->innerload_daily > bq. 2012-10-12 14:54:11,031 [main] ERROR org.apache.pig.tools.grunt.Grunt - > ERROR 2000: Error processing rule ColumnMapKeyPrune. Try -t ColumnMapKeyPrune -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators For more information on JIRA, see: http://www.atlassian.com/software/jira