tjbanghart commented on code in PR #4658: URL: https://github.com/apache/calcite/pull/4658#discussion_r2583790673
########## 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: Good questions, I've updated the PR so `Combine` now returns one row per input query. Each row holds an array of maps, where each map represents a row from that query with column names as keys. We are constrained by JDBC's limitations of returning a single result set per query but this would allow iterating over individual query results with `resultSet.next()` and then iterating over each query's results via the array. For example, combining: `SELECT name FROM depts;` and `SELECT empid, name, deptno FROM emps WHERE deptno = 10;` Yields: ``` -- Row 1 QUERY=[ {name=Sales}, {name=Marketing}, {name=HR} ], -- Row 2 QUERY=[ {empid=100, name=Bill, deptno=10}, {empid=150, name=Sebastian, deptno=10} , {empid=110, name=Theodore, deptno=10} ] ``` Later, we should probably allow for aliases for queries so they don't have the generic `QUERY` column label but that may be more challenging (see the syntax for `MULTI` described in [CALCITE-6188](https://issues.apache.org/jira/browse/CALCITE-6188)). -- 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]
