libenchao commented on code in PR #2848:
URL: https://github.com/apache/calcite/pull/2848#discussion_r1027061254
##
core/src/main/java/org/apache/calcite/rel/rules/SemiJoinRule.java:
##
@@ -232,6 +234,84 @@ default JoinToSemiJoinRuleConfig
withOperandFor(Class 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());
+ if (unique != null && unique) {
+final RelBuilder builder = call.builder();
+switch (join.getJoinType()) {
+case INNER:
+ builder.push(left);
+ builder.push(right);
+ builder.join(JoinRelType.SEMI, join.getCondition());
+ break;
+case LEFT:
+ builder.push(left);
+ break;
+default:
+ throw new AssertionError(join.getJoinType());
+}
+builder.project(project.getProjects());
Review Comment:
@sdreynolds thanks for catching this, I noticed that you have opened
CALCITE-5391 to track this, let's go to there for further discussions.
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