Optimizer throw error on self-joins
-----------------------------------
Key: PIG-859
URL: https://issues.apache.org/jira/browse/PIG-859
Project: Pig
Issue Type: Bug
Components: impl
Affects Versions: 0.3.0
Reporter: Ashutosh Chauhan
Fix For: 0.4.0
Doing self-join results in exception thrown by Optimizer. Consider the
following query
{code}
grunt> A = load 'a';
grunt> B = Join A by $0, A by $0;
grunt> explain B;
2009-06-20 15:51:38,303 [main] ERROR org.apache.pig.tools.grunt.Grunt -
ERROR 1094: Attempt to insert between two nodes that were not connected.
Details at logfile: pig_1245538027026.log
{code}
Relevant stack-trace from log-file:
{code}
Caused by: org.apache.pig.impl.plan.optimizer.OptimizerException: ERROR
2047: Internal error. Unable to introduce split operators.
at
org.apache.pig.impl.logicalLayer.optimizer.ImplicitSplitInserter.transform(ImplicitSplitInserter.java:163)
at
org.apache.pig.impl.logicalLayer.optimizer.LogicalOptimizer.optimize(LogicalOptimizer.java:163)
at org.apache.pig.PigServer.compileLp(PigServer.java:844)
at org.apache.pig.PigServer.compileLp(PigServer.java:781)
at org.apache.pig.PigServer.getStorePlan(PigServer.java:723)
at org.apache.pig.PigServer.explain(PigServer.java:566)
... 8 more
Caused by: org.apache.pig.impl.plan.PlanException: ERROR 1094: Attempt
to insert between two nodes that were not connected.
at
org.apache.pig.impl.plan.OperatorPlan.doInsertBetween(OperatorPlan.java:500)
at
org.apache.pig.impl.plan.OperatorPlan.insertBetween(OperatorPlan.java:480)
at
org.apache.pig.impl.logicalLayer.optimizer.ImplicitSplitInserter.transform(ImplicitSplitInserter.java:139)
... 13 more
{code}
A possible workaround is:
{code}
grunt> A = load 'a';
grunt> B = load 'a';
grunt> C = join A by $0, B by $0;
grunt> explain C;
{code}
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