cloud-fan commented on code in PR #50921: URL: https://github.com/apache/spark/pull/50921#discussion_r2185390225
########## sql/catalyst/src/main/java/org/apache/spark/sql/connector/read/SupportsPushDownJoin.java: ########## @@ -0,0 +1,81 @@ +/* + * 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.spark.sql.connector.read; + +import java.util.Optional; + +import org.apache.spark.annotation.Evolving; +import org.apache.spark.sql.connector.expressions.filter.Predicate; +import org.apache.spark.sql.connector.join.JoinType; +import org.apache.spark.sql.types.StructType; + +/** + * A mix-in interface for {@link ScanBuilder}. Data sources can implement this interface to + * push down join operators. + * + * @since 4.1.0 + */ +@Evolving +public interface SupportsPushDownJoin extends ScanBuilder { + /** + * Returns true if the other side of the join is compatible with the + * current {@code SupportsPushDownJoin} for a join push down, meaning both sides can be + * processed together within the same underlying data source. + * + * <p>For example, JDBC connectors are compatible if they use the same + * host, port, username, and password.</p> + */ + boolean isOtherSideCompatibleForJoin(SupportsPushDownJoin other); + + /** + * Joining 2 {@code SupportsPushDownJoin} can be problematic if there are columns with duplicate + * names. The {@code SupportsPushDownJoin} implementation should deal with this problem. + * + * This method returns the merged schema that will be preserved to {@code SupportsPushDownJoin}'s + * schema after {@code pushDownJoin} call succeeds. + * + * @param other {@code SupportsPushDownJoin} that this {@code SupportsPushDownJoin} + * gets joined with. + * @param requiredSchema required columns needed for this {@code SupportsPushDownJoin}. + * @param otherSideRequiredSchema required columns needed for other {@code SupportsPushDownJoin}. + * @return merged schema. If ambiguous names are forbidden, the merged schema should resolve that. + */ + StructType getJoinedSchema( + SupportsPushDownJoin other, + StructType requiredSchema, + StructType otherSideRequiredSchema + ); + + /** + * Pushes down the join of the current {@code SupportsPushDownJoin} and the other side of join + * {@code SupportsPushDownJoin}. + * + * @param other {@code SupportsPushDownJoin} that this {@code SupportsPushDownJoin} + * gets joined with. + * @param requiredSchema required output schema after join push down. + * @param joinType the type of join. + * @param condition join condition. + * @return True if join has been successfully pushed down. + */ + boolean pushDownJoin( Review Comment: Thinking about it once more, let's simplify the API further by asking Spark to generate unique column names: ``` boolean pushDownJoin( SupportsPushDownJoin other, JoinType joinType, ColWithAlias[] leftSideCols, ColWithAlias[] leftSideCols, Predicate condition ) // Alias can be null to indicate no alias class ColWithAlias(col: String, alias: String) ``` -- 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: reviews-unsubscr...@spark.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For additional commands, e-mail: reviews-h...@spark.apache.org
