Github user amansinha100 commented on a diff in the pull request:
https://github.com/apache/drill/pull/889#discussion_r135199961
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/join/JoinUtils.java
---
@@ -231,6 +236,12 @@ public static boolean isScalarSubquery(RelNode root) {
return true;
}
}
+ if (!hasMoreInputs && currentRel != null) {
+ Double rowSize =
RelMetadataQuery.instance().getMaxRowCount(currentRel);
--- End diff --
Actually, I am thinking this entire method isScalarSubquery() should be
rewritten to call RelMetadataQuery.getMaxRowCount(). Originally, when this
was written, the max row count interface was not available.
I think your use case is somewhat specific that the table has 1 row.
However, suppose we had LIMIT 1 in the subquery, we could still treat it as
scalar since it would produce at most 1 row. My thought is instead of solving
for your specific table scan case, we might as well address the generalized
scalar check since Calcite already provides it.
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