suibianwanwank commented on code in PR #4244:
URL: https://github.com/apache/calcite/pull/4244#discussion_r2017365349
##########
core/src/test/java/org/apache/calcite/test/RelOptRulesTest.java:
##########
@@ -10048,4 +10048,35 @@ private void
checkLoptOptimizeJoinRule(LoptOptimizeJoinRule rule) {
sql(sql).withRule(CoreRules.INTERSECT_TO_EXISTS)
.checkUnchanged();
}
+
+ /** Test case for <a
href="https://issues.apache.org/jira/browse/CALCITE-6891";>
+ * [CALCITE-6891] Implement IntersectReorderRule</a>. */
+ @Test void testIntersectReorderRule() {
+ final String sql = "select deptno from emp\n"
+ + "intersect\n"
+ + "select deptno from dept\n";
+
+ sql(sql).withVolcanoPlanner(true, p -> {
Review Comment:
Maybe it would be clearer to apply the rules by adding different filters for
the same scan in the test case.
##########
core/src/main/java/org/apache/calcite/rel/rules/IntersectReorderRule.java:
##########
@@ -0,0 +1,99 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to you under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.calcite.rel.rules;
+
+import org.apache.calcite.plan.RelOptRuleCall;
+import org.apache.calcite.plan.RelRule;
+import org.apache.calcite.rel.RelNode;
+import org.apache.calcite.rel.core.Intersect;
+import org.apache.calcite.rel.logical.LogicalIntersect;
+import org.apache.calcite.rel.metadata.RelMetadataQuery;
+import org.apache.calcite.tools.RelBuilder;
+import org.apache.calcite.util.Pair;
+
+import org.immutables.value.Value;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.stream.Collectors;
+
+/**
+ * Planner rule that reorders inputs of an {@link Intersect} to put smaller
inputs first.
+ * This helps reduce the size of intermediate results.
+ *
+ * <p>Intersect(A, B, ...) where B is smallest will reorder to Intersect(B, A,
...)
+ */
[email protected]
+public class IntersectReorderRule extends RelRule<IntersectReorderRule.Config>
+ implements SubstitutionRule {
+ /** Creates an IntersectReorderRule. */
+ protected IntersectReorderRule(Config config) {
+ super(config);
+ }
+
+ @Override public void onMatch(RelOptRuleCall call) {
+ final Intersect intersect = call.rel(0);
Review Comment:
I suggest it could be simpler here, For example:
```
final Intersect intersect = call.rel(0);
final RelMetadataQuery mq = call.getMetadataQuery();
final List<RelNode> inputs = intersect.getInputs();
List<RelNode> sortedInputs = inputs.stream()
.sorted(Comparator.comparingDouble(input -> mq.getRowCount(input)))
.collect(Collectors.toList());
if (inputs.equals(sortedInputs)) {
return;
}
final RelBuilder relBuilder = call.builder();
relBuilder.pushAll(sortedInputs);
relBuilder.intersect(intersect.all, sortedInputs.size());
call.transformTo(relBuilder.build());
```
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