Diamond query optimization throws error in JOIN -----------------------------------------------
Key: PIG-1113 URL: https://issues.apache.org/jira/browse/PIG-1113 Project: Pig Issue Type: Bug Reporter: Ankur The following script results in 1 M/R job as a result of diamond query optimization but the script fails. set1 = LOAD 'set1' USING PigStorage as (a:chararray, b:chararray, c:chararray); set2 = LOAD 'set2' USING PigStorage as (a: chararray, b:chararray, c:bag{}); set2_1 = FOREACH set2 GENERATE a as f1, b as f2, (chararray) 0 as f3; set2_2 = FOREACH set2 GENERATE a as f1, FLATTEN((IsEmpty(c) ? null : c)) as f2, (chararray) 1 as f3; all_set2 = UNION set2_1, set2_2; joined_sets = JOIN set1 BY (a,b), all_set2 BY (f2,f3); dump joined_sets; And here is the error org.apache.pig.backend.executionengine.ExecException: ERROR 1071: Cannot convert a bag to a String at org.apache.pig.data.DataType.toString(DataType.java:739) at org.apache.pig.backend.hadoop.executionengine.physicalLayer.expressionOperators.POCast.getNext(POCast.java:625) at org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POForEach.processPlan(POForEach.java:364) at org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POForEach.getNext(POForEach.java:288) at org.apache.pig.backend.hadoop.executionengine.physicalLayer.PhysicalOperator.processInput(PhysicalOperator.java:260) at org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POLocalRearrange.getNext(POLocalRearrange.java:256) at org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POUnion.getNext(POUnion.java:162) at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigMapBase.runPipeline(PigMapBase.java:247) at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigMapBase.map(PigMapBase.java:238) at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigMapReduce$Map.map(PigMapReduce.java:93) at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:50) at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:358) at org.apache.hadoop.mapred.MapTask.run(MapTask.java:307) at org.apache.hadoop.mapred.Child.main(Child.java:159) -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online.