yashmayya commented on code in PR #2848:
URL: https://github.com/apache/calcite/pull/2848#discussion_r1613307615
##########
core/src/main/java/org/apache/calcite/rel/rules/SemiJoinRule.java:
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@@ -232,6 +234,84 @@ default JoinToSemiJoinRuleConfig
withOperandFor(Class<Join> joinClass,
}
}
+ /**
+ * SemiJoinRule that matches a Project on top of a Join with a RelNode
+ * which is unique for Join's right keys.
+ *
+ * @see CoreRules#JOIN_ON_UNIQUE_TO_SEMI_JOIN */
+ public static class JoinOnUniqueToSemiJoinRule extends SemiJoinRule {
+
+ /** Creates a JoinOnUniqueToSemiJoinRule. */
+ protected JoinOnUniqueToSemiJoinRule(JoinOnUniqueToSemiJoinRuleConfig
config) {
+ super(config);
+ }
+
+ @Override public boolean matches(RelOptRuleCall call) {
+ final Project project = call.rel(0);
+ final Join join = call.rel(1);
+ final RelNode left = call.rel(2);
+
+ final ImmutableBitSet bits =
+ RelOptUtil.InputFinder.bits(project.getProjects(), null);
+ final ImmutableBitSet rightBits =
+ ImmutableBitSet.range(left.getRowType().getFieldCount(),
+ join.getRowType().getFieldCount());
+ return !bits.intersects(rightBits);
+ }
+
+ @Override public void onMatch(RelOptRuleCall call) {
+ final Project project = call.rel(0);
+ final Join join = call.rel(1);
+ final RelNode left = call.rel(2);
+ final RelNode right = call.rel(3);
+
+ final JoinInfo joinInfo = join.analyzeCondition();
+ final RelOptCluster cluster = join.getCluster();
+ final RelMetadataQuery mq = cluster.getMetadataQuery();
+ final Boolean unique = mq.areColumnsUnique(right, joinInfo.rightSet());
Review Comment:
This doesn't take into account any `nonEquiConditions` on the join? We also
aren't verifying beforehand whether the join is an equi-join as is being done
for the other two semi-join rules `ProjectToSemiJoinRule` and
`JoinToSemiJoinRule` here -
https://github.com/apache/calcite/blob/4def07066b6cb370e37739985b19f6e6b408addb/core/src/main/java/org/apache/calcite/rel/rules/SemiJoinRule.java#L96-L98
@libenchao do you think this is a potential bug in the
`JoinOnUniqueToSemiJoinRule`?
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