jamesstarr commented on a change in pull request #2393:
URL: https://github.com/apache/calcite/pull/2393#discussion_r613587690
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File path: core/src/main/java/org/apache/calcite/tools/RelBuilder.java
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@@ -2368,24 +2368,28 @@ public RelBuilder join(JoinRelType joinType, RexNode
condition,
}
if (correlate) {
final CorrelationId id = Iterables.getOnlyElement(variablesSet);
- final ImmutableBitSet requiredColumns =
- RelOptUtil.correlationColumns(id, right.rel);
if (!RelOptUtil.notContainsCorrelation(left.rel, id, Litmus.IGNORE)) {
throw new IllegalArgumentException("variable " + id
+ " must not be used by left input to correlation");
}
+ // Correlate does not have an ON clause.
switch (joinType) {
case LEFT:
- // Correlate does not have an ON clause.
- // For a LEFT correlate, predicate must be evaluated first.
- // For INNER, we can defer.
+ case SEMI:
+ case ANTI:
+ // For a LEFT/SEMI/ANTI, predicate must be evaluated first.
stack.push(right);
filter(condition.accept(new Shifter(left.rel, id, right.rel)));
right = stack.pop();
break;
- default:
+ case INNER:
+ // For INNER, we can defer.
postCondition = condition;
+ break;
+ default:
+ throw new IllegalArgumentException("Correlated " + joinType + " join
is not supported");
}
+ final ImmutableBitSet requiredColumns =
RelOptUtil.correlationColumns(id, right.rel);
Review comment:
I am not sure if this is place to do it, but should we detect if
correlated variables only occur in the condition and emit a normal join if that
is case?
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