Github user hsuanyi commented on a diff in the pull request: https://github.com/apache/drill/pull/407#discussion_r55597867 --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/union/UnionAllRecordBatch.java --- @@ -294,13 +313,41 @@ public UnionAllInput(UnionAllRecordBatch unionAllRecordBatch, RecordBatch left, rightSide = new OneSideInput(right); } + private boolean isBothSideEmpty() { + return leftIsFinish && rightIsFinish; + } + public IterOutcome nextBatch() throws SchemaChangeException { if(upstream == RecordBatch.IterOutcome.NOT_YET) { IterOutcome iterLeft = leftSide.nextBatch(); switch(iterLeft) { case OK_NEW_SCHEMA: - break; + whileLoop: + while(leftSide.getRecordBatch().getRecordCount() == 0) { + iterLeft = leftSide.nextBatch(); + + switch(iterLeft) { + case STOP: + case OUT_OF_MEMORY: + return iterLeft; + + case NONE: --- End diff -- The while is for the case where the first few batches are empty and then union-all receive NONE. So we need to replicate this logic to right side too.
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