NPE in MergeJoinStrategy when using joins with a particular limit value ----------------------------------------------------------------------- Key: TEIID-5686 URL: https://issues.jboss.org/browse/TEIID-5686 Project: Teiid Issue Type: Bug Components: Query Engine Affects Versions: 12.0 Environment: teiid-12.0.0 on WildFly Full 14.0.1.Final (WildFly Core 6.0.2.Final) Reporter: dalex dalex Assignee: Steven Hawkins Priority: Major Fix For: 12.2 When running the following query (IMPORTANT: you shouldn't use row limit): {code:sql} begin declare integer i=0; while (i < 2) begin select * from "test_tables_pg.test_a" t0 JOIN "test_tables_pg.test_e" t1 ON true JOIN "test_tables_pg.test_e" t2 ON true JOIN views.v t3 on true JOIN views.v t4 on true limit 257 ; i=i+1; end end ;; {code} teiid throws out the following NPE: {code:noformat} 2019-03-13 13:50:28,582 ERROR [org.teiid.PROCESSOR] (Worker4_QueryProcessorQueue233) InwGU8fhfbja TEIID30019 Unexpected exception for request InwGU8fhfbja.22: java.lang.NullPointerEx ception at org.teiid.query.processor.relational.MergeJoinStrategy.compareToPrevious(MergeJoinStrategy.java:284) at org.teiid.query.processor.relational.MergeJoinStrategy.process(MergeJoinStrategy.java:238) at org.teiid.query.processor.relational.JoinNode.nextBatchDirectInternal(JoinNode.java:260) at org.teiid.query.processor.relational.JoinNode.nextBatchDirect(JoinNode.java:195) at org.teiid.query.processor.relational.RelationalNode.nextBatch(RelationalNode.java:277) at org.teiid.query.processor.relational.LimitNode.nextBatchDirect(LimitNode.java:98) at org.teiid.query.processor.relational.RelationalNode.nextBatch(RelationalNode.java:277) at org.teiid.query.processor.relational.ProjectNode.nextBatchDirect(ProjectNode.java:146) at org.teiid.query.processor.relational.RelationalNode.nextBatch(RelationalNode.java:277) at org.teiid.query.processor.relational.RelationalPlan.nextBatch(RelationalPlan.java:141) at org.teiid.query.processor.QueryProcessor.nextBatchDirect(QueryProcessor.java:148) at org.teiid.query.processor.QueryProcessor.nextBatch(QueryProcessor.java:111) at org.teiid.query.processor.BatchIterator.finalRow(BatchIterator.java:65) at org.teiid.common.buffer.AbstractTupleSource.getCurrentTuple(AbstractTupleSource.java:66) at org.teiid.query.processor.BatchIterator.getCurrentTuple(BatchIterator.java:80) at org.teiid.common.buffer.AbstractTupleSource.nextTuple(AbstractTupleSource.java:44) at org.teiid.query.processor.proc.ProcedurePlan.nextBatchDirect(ProcedurePlan.java:303) at org.teiid.query.processor.proc.ProcedurePlan.nextBatch(ProcedurePlan.java:269) at org.teiid.query.processor.QueryProcessor.nextBatchDirect(QueryProcessor.java:148) at org.teiid.query.processor.QueryProcessor.nextBatch(QueryProcessor.java:111) at org.teiid.query.processor.BatchCollector.collectTuples(BatchCollector.java:160) at org.teiid.query.processor.BatchCollector.collectTuples(BatchCollector.java:142) at org.teiid.dqp.internal.process.RequestWorkItem.processMore(RequestWorkItem.java:492) at org.teiid.dqp.internal.process.RequestWorkItem.process(RequestWorkItem.java:362) at org.teiid.dqp.internal.process.AbstractWorkItem.run(AbstractWorkItem.java:43) at org.teiid.dqp.internal.process.RequestWorkItem.run(RequestWorkItem.java:285) at org.teiid.dqp.internal.process.DQPWorkContext.runInContext(DQPWorkContext.java:281) at org.teiid.dqp.internal.process.ThreadReuseExecutor$RunnableWrapper.run(ThreadReuseExecutor.java:113) at org.teiid.dqp.internal.process.ThreadReuseExecutor$3.run(ThreadReuseExecutor.java:199) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) at java.lang.Thread.run(Thread.java:745) {code}