Github user arina-ielchiieva commented on a diff in the pull request: https://github.com/apache/drill/pull/889#discussion_r131871049 --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/join/JoinUtils.java --- @@ -204,24 +205,28 @@ public static void addLeastRestrictiveCasts(LogicalExpression[] leftExpressions, /** * Utility method to check if a subquery (represented by its root RelNode) is provably scalar. Currently - * only aggregates with no group-by are considered scalar. In the future, this method should be generalized - * to include more cases and reconciled with Calcite's notion of scalar. + * only aggregates with no group-by and sub input rel with one row are considered scalar. In the future, + * this method should be generalized to include more cases and reconciled with Calcite's notion of scalar. * @param root The root RelNode to be examined * @return True if the root rel or its descendant is scalar, False otherwise */ public static boolean isScalarSubquery(RelNode root) { DrillAggregateRel agg = null; - RelNode currentrel = root; - while (agg == null && currentrel != null) { - if (currentrel instanceof DrillAggregateRel) { - agg = (DrillAggregateRel)currentrel; - } else if (currentrel instanceof RelSubset) { - currentrel = ((RelSubset)currentrel).getBest() ; - } else if (currentrel.getInputs().size() == 1) { + RelNode currentRel = root; + boolean hasMoreInputs = false; + while (agg == null && currentRel != null) { + if (currentRel instanceof DrillAggregateRel) { + agg = (DrillAggregateRel)currentRel; + } else if (currentRel instanceof RelSubset) { + currentRel = ((RelSubset)currentRel).getBest() ; + } else if (currentRel.getInputs().size() == 1) { // If the rel is not an aggregate or RelSubset, but is a single-input rel (could be Project, // Filter, Sort etc.), check its input - currentrel = currentrel.getInput(0); + currentRel = currentRel.getInput(0); } else { + if(currentRel.getInputs().size()>1){ --- End diff -- Please add spaces: `if (currentRel.getInputs().size() > 1) {`
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