xiedeyantu commented on code in PR #4658: URL: https://github.com/apache/calcite/pull/4658#discussion_r2583053493
########## core/src/main/java/org/apache/calcite/rel/rules/CombineSimpleEquivalenceRule.java: ########## @@ -0,0 +1,227 @@ +/* + * 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.RelDigest; +import org.apache.calcite.plan.RelOptRuleCall; +import org.apache.calcite.plan.RelOptUtil; +import org.apache.calcite.plan.RelRule; +import org.apache.calcite.plan.SpoolRelOptTable; +import org.apache.calcite.rel.RelCommonExpressionBasicSuggester; +import org.apache.calcite.rel.RelHomogeneousShuttle; +import org.apache.calcite.rel.RelNode; +import org.apache.calcite.rel.core.Combine; +import org.apache.calcite.rel.core.RelFactories; +import org.apache.calcite.rel.core.Spool; +import org.apache.calcite.rel.logical.LogicalTableScan; +import org.apache.calcite.rel.logical.LogicalTableSpool; +import org.apache.calcite.rel.metadata.RelMetadataQuery; + +import com.google.common.collect.ImmutableList; + +import org.immutables.value.Value; + +import java.util.Collection; +import java.util.HashMap; +import java.util.HashSet; +import java.util.Map; +import java.util.Set; + +/** + * Rule that optimizes a {@link Combine} operator by detecting shared sub-expressions + * across its inputs and introducing {@link Spool}s to avoid redundant computation. + * + * <p>This rule identifies structurally equivalent sub-plans within a Combine's inputs + * and replaces them with a spool pattern: the first occurrence becomes a producer + * (TableSpool that materializes the result), and subsequent occurrences become + * consumers (TableScan reading from the spooled data). + * + * <h2>Example</h2> + * + * <p>Consider two queries combined that share a common filtered table scan: + * + * <pre>{@code Review Comment: Excellent documentation, thank you. ########## core/src/test/java/org/apache/calcite/test/enumerable/EnumerableCombineTest.java: ########## @@ -0,0 +1,126 @@ +/* + * 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.test.enumerable; + +import org.apache.calcite.adapter.java.ReflectiveSchema; +import org.apache.calcite.config.CalciteConnectionProperty; +import org.apache.calcite.config.Lex; +import org.apache.calcite.test.CalciteAssert; +import org.apache.calcite.test.schemata.hr.HrSchema; + +import org.junit.jupiter.api.Test; + +/** + * Unit tests for {@link org.apache.calcite.adapter.enumerable.EnumerableCombine}. + */ +class EnumerableCombineTest { + + /** + * Test that executes two simple queries combined. + * Query 1: Select employee names from department 10 + * Query 2: Select department names + * + * <p>The Combine operator returns results in a structured format where each + * query's results are grouped: {@code QUERY_0={...}; QUERY_1={...}} + */ + @Test void testCombineTwoQueries() { + tester(new HrSchema()) + .withRel( + builder -> { + // Query 1: SELECT name FROM emps WHERE deptno = 10 + builder.scan("s", "emps") + .filter( + builder.equals( + builder.field("deptno"), + builder.literal(10))) + .project(builder.field("name")); + + // Query 2: SELECT name FROM depts + builder.scan("s", "depts") + .project(builder.field("name")); + + // Combine both queries + return builder.combine(2).build(); + }) + .returnsUnordered( Review Comment: I see that `AssertQuery.returnsUnordered(String... lines)` can return multiple lines. In JdbcTest, some examples use the format `{column_name}={value}`, such as `returnsUnordered("DID2=1", "DID2=2")`. I'm not sure if the current `QUERY_0=xxx `format is well-suited for future Quidem tests. Assuming that in the future I could use a setting like `set enable_combine = true` to allow multiple SQL statements to execute simultaneously, would we still want to obtain two separate result sets—just like when the two SQL statements are executed separately? ########## core/src/test/java/org/apache/calcite/test/enumerable/EnumerableCombineTest.java: ########## @@ -0,0 +1,126 @@ +/* + * 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.test.enumerable; + +import org.apache.calcite.adapter.java.ReflectiveSchema; +import org.apache.calcite.config.CalciteConnectionProperty; +import org.apache.calcite.config.Lex; +import org.apache.calcite.test.CalciteAssert; +import org.apache.calcite.test.schemata.hr.HrSchema; + +import org.junit.jupiter.api.Test; + +/** + * Unit tests for {@link org.apache.calcite.adapter.enumerable.EnumerableCombine}. + */ +class EnumerableCombineTest { + + /** + * Test that executes two simple queries combined. + * Query 1: Select employee names from department 10 + * Query 2: Select department names + * + * <p>The Combine operator returns results in a structured format where each + * query's results are grouped: {@code QUERY_0={...}; QUERY_1={...}} + */ + @Test void testCombineTwoQueries() { Review Comment: Is it possible to add a case where multiple SQL queries return different numbers of columns? -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
