xuzifu666 commented on code in PR #4684:
URL: https://github.com/apache/calcite/pull/4684#discussion_r2617757239
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core/src/main/java/org/apache/calcite/rel/metadata/RelMdExpressionLineage.java:
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@@ -387,6 +389,30 @@ protected RelMdExpressionLineage() {}
return createAllPossibleExpressions(rexBuilder, outputExpression, mapping);
}
+ private static @Nullable Set<RexNode>
getExpressionLineageForProjectExpr(RelMetadataQuery mq,
+ RelNode input, RexNode expr) {
+ if (expr instanceof RexSubQuery) {
+ return getLineageFromSubQuery(mq, (RexSubQuery) expr);
+ }
+ if (extractInputRefs(expr).isEmpty()) {
+ return ImmutableSet.of(expr);
+ }
+ return mq.getExpressionLineage(input, expr);
+ }
+
+ private static Set<RexNode> getLineageFromSubQuery(RelMetadataQuery mq,
+ RexSubQuery subQuery) {
+ final List<RelDataTypeField> fields =
subQuery.rel.getRowType().getFieldList();
+ if (!fields.isEmpty()) {
+ final RexInputRef subRef = RexInputRef.of(0, fields);
+ final Set<RexNode> result = mq.getExpressionLineage(subQuery.rel,
subRef);
+ if (result != null) {
Review Comment:
Okay, I've looked at this logic, and it seems that NULL and empty have
equivalent effects. If that's indeed the case, then this processing is correct.
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