[PIG-1812] Problem with DID_NOT_FIND_LOAD_ONLY_MAP_PLAN

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.7.0, 0.8.0
• Fix Version/s: 0.8.1

Environment

RHEL, Pig 0.8.0

• Hadoop Flags: Reviewed
• Assignee: Daniel Dai
• Reporter: xianyu
• Created: 20/Jan/11 02:06
• Updated: 25/Apr/11 21:27
• Resolved: 31/Jan/11 22:01

Description

Hi,
I have the following input files:

pkg.txt

a 3

{(123,1.0),(236,2.0)}

a 3

{(236,1.0)}

model.txt

a 123 2 0.33
a 236 2 0.5

My script is listed below:

A = load 'pkg.txt' using PigStorage('\t') as (pkg:chararray, ts:int, cat_bag:

{t:(id:chararray, wht:float)}

);

M = load 'model.txt' using PigStorage('\t') as (pkg:chararray, cat_id:chararray, ts:int, score:double);

B = foreach A generate ts, pkg, flatten(cat_bag.id) as (cat_id:chararray);

B = distinct B;

H1 = cogroup M by (pkg, cat_id) inner, B by (pkg, cat_id);

H2 = foreach H1 {
I = order M by ts;
J = order B by ts;
generate flatten(group) as (pkg:chararray, cat_id:chararray), J.ts as tsorig, I.ts as tsmap;
}

dump H2;

When running this script, I got a warning about "Encountered Warning DID_NOT_FIND_LOAD_ONLY_MAP_PLAN 1 time(s)" and pig error log as below:

Pig Stack Trace

---------------

ERROR 2043: Unexpected error during execution.
org.apache.pig.impl.logicalLayer.FrontendException: ERROR 1066: Unable to open iterator for alias H2
at org.apache.pig.PigServer.openIterator(PigServer.java:764)
at org.apache.pig.tools.grunt.GruntParser.processDump(GruntParser.java:612)
at org.apache.pig.tools.pigscript.parser.PigScriptParser.parse(PigScriptParser.java:303)
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:500)
at org.apache.pig.Main.main(Main.java:107)
Caused by: org.apache.pig.PigException: ERROR 1002: Unable to store alias H2
at org.apache.pig.PigServer.storeEx(PigServer.java:888)
at org.apache.pig.PigServer.store(PigServer.java:826)
at org.apache.pig.PigServer.openIterator(PigServer.java:738)
... 7 more
Caused by: org.apache.pig.backend.executionengine.ExecException: ERROR 2043: Unexpected error during execution.
at org.apache.pig.backend.hadoop.executionengine.HExecutionEngine.execute(HExecutionEngine.java:403)
at org.apache.pig.PigServer.executeCompiledLogicalPlan(PigServer.java:1208)
at org.apache.pig.PigServer.storeEx(PigServer.java:884)
... 9 more
Caused by: java.lang.ClassCastException: org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POLoad cannot be cast to org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POLocalRearrange
at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.SecondaryKeyOptimizer.visitMROp(SecondaryKeyOptimizer.java:352)
at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MapReduceOper.visit(MapReduceOper.java:246)
at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MapReduceOper.visit(MapReduceOper.java:41)
at org.apache.pig.impl.plan.DepthFirstWalker.depthFirst(DepthFirstWalker.java:69)
at org.apache.pig.impl.plan.DepthFirstWalker.depthFirst(DepthFirstWalker.java:71)
at org.apache.pig.impl.plan.DepthFirstWalker.walk(DepthFirstWalker.java:52)
at org.apache.pig.impl.plan.PlanVisitor.visit(PlanVisitor.java:51)
at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MapReduceLauncher.compile(MapReduceLauncher.java:498)
at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MapReduceLauncher.launchPig(MapReduceLauncher.java:117)
at org.apache.pig.backend.hadoop.executionengine.HExecutionEngine.execute(HExecutionEngine.java:378)
... 11 more

But, when I removed the DISTINCT statement before COGROUP, i.e. "B = distinct B;" this script can run smoothly. I have also tried other reducer side operations like ORDER, it seems that they will also trigger above error. This is really very confusing.