danny0405 commented on a change in pull request #1157: [CALCITE-2969] Improve
design of join-like relational expressions
URL: https://github.com/apache/calcite/pull/1157#discussion_r283682678
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File path: core/src/main/java/org/apache/calcite/rel/core/Join.java
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@@ -230,6 +237,15 @@ public boolean isSemiJoinDone() {
return false;
}
+ /**
+ * Returns whether this Join is a semijoin.
+ *
+ * @return true if this is semi but without correlate variables.
+ */
+ public boolean isSemiJoin() {
Review comment:
@rubenada I think `Join#getJoinType().returnsJustFirstInput()` is ok for the
`ANTI` case, the reason i add a method for semiJoin is that there are so many
cases we have to make decision if it is a SemiJoin type(for rowType or for cost
computation or else), after we add in `ANTI` join, i think we just need to add
a new method `isAntiJoin`, i'm not sure if we can unify the logic for `ANTI`
join where SemiJoin appears(very probably not), if we can, i agree with you to
move the `returnsJustFirstInput()` method into `Join`.
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