libenchao commented on code in PR #2848:
URL: https://github.com/apache/calcite/pull/2848#discussion_r913747509
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core/src/main/java/org/apache/calcite/rel/rules/SemiJoinRule.java:
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@@ -232,6 +237,79 @@ default JoinToSemiJoinRuleConfig
withOperandFor(Class<Join> joinClass,
}
}
+ /**
+ * SemiJoinRule that matches 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 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);
+
+ // return if right's fields are used.
+ final ImmutableBitSet bits =
+ RelOptUtil.InputFinder.bits(project.getProjects(), null);
+ final ImmutableBitSet rightBits =
+ ImmutableBitSet.range(left.getRowType().getFieldCount(),
+ join.getRowType().getFieldCount());
+ if (bits.intersects(rightBits)) {
+ return;
+ }
+
+ 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:
+ case SEMI:
+ 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());
+ call.transformTo(builder.build());
+ }
+ }
+
+ /**
+ * Rule configuration.
+ */
+ @Value.Immutable
+ public interface JoinOnUniqueToSemiJoinRuleConfig extends
SemiJoinRule.Config {
+ JoinOnUniqueToSemiJoinRuleConfig DEFAULT =
ImmutableJoinOnUniqueToSemiJoinRuleConfig.of()
+ .withDescription("SemiJoinRule:unique")
+ .withOperandSupplier(b ->
+ b.operand(Project.class).oneInput(
+ b2 ->
b2.operand(Join.class).predicate(SemiJoinRule::isJoinTypeSupported).inputs(
+ b3 -> b3.operand(RelNode.class).anyInputs(),
+ b4 -> b4.operand(RelNode.class).anyInputs()
Review Comment:
We need to check whether the right input is unique for Join's keys, hence we
need at least the right input.
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