huaxingao commented on code in PR #44119: URL: https://github.com/apache/spark/pull/44119#discussion_r1431953328
########## sql/core/src/main/scala/org/apache/spark/sql/MergeIntoWriter.scala: ########## @@ -0,0 +1,316 @@ +/* + * 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 + +import org.apache.spark.annotation.Experimental +import org.apache.spark.sql.catalyst.analysis.UnresolvedRelation +import org.apache.spark.sql.catalyst.expressions.Expression +import org.apache.spark.sql.catalyst.plans.logical.{Assignment, DeleteAction, InsertAction, InsertStarAction, MergeAction, MergeIntoTable, UpdateAction, UpdateStarAction} +import org.apache.spark.sql.errors.QueryExecutionErrors +import org.apache.spark.sql.functions.expr + +/** + * `MergeIntoWriter` provides methods to define and execute merge actions based + * on specified conditions. + * + * @tparam T the type of data in the Dataset. + * @param table the name of the target table for the merge operation. + * @param ds the source Dataset to merge into the target table. + * + * @since 4.0.0 + */ +@Experimental +class MergeIntoWriter[T] private[sql] (table: String, ds: Dataset[T]) + extends DataFrameWriterV2[T](table, ds) { + + var on: Option[Column] = None + var matchedActions: Seq[MergeAction] = Seq.empty[MergeAction] + var notMatchedActions: Seq[MergeAction] = Seq.empty[MergeAction] + var notMatchedBySourceActions: Seq[MergeAction] = Seq.empty[MergeAction] + + /** + * Specifies the merge condition. + * + * Sets the condition to be used for merging data. This condition is used to determine + * how rows from the source DataFrame are matched with rows in the target table. + * + * @param condition a `Column` representing the merge condition. + * @return the current `MergeIntoWriter` instance with the specified merge condition set. + */ + def on(condition: Column): MergeIntoWriter[T] = { + this.on = Some(condition) + this + } + + /** + * Initialize a `WhenMatched` action without any condition. + * + * This `WhenMatched` can be followed by one of the following merge actions: + * - `updateAll`: Update all the target table fields with source dataset fields. + * - `update(Map)`: Update all the target table records while changing only + * a subset of fields based on the provided assignment. + * - `delete`: Delete all the target table records. + * + * @return a new `WhenMatched` object. + */ + def whenMatched(): WhenMatched[T] = { + new WhenMatched[T](this, None) + } + + /** + * Initialize a `WhenMatched` action with a condition. + * + * This `WhenMatched` action will be executed if and only if the specified `condition` + * is satisfied. + * + * This `WhenMatched` can be followed by one of the following merge actions: + * - `updateAll`: Update all the target table fields with source dataset fields. + * - `update(Map)`: Update all the target table records while changing only + * a subset of fields based on the provided assignment. + * - `delete`: Delete all the target table records. + * + * @param condition a `Column` representing the condition to be evaluated for the action. + * @return a new `WhenMatched` object configured with the specified condition. + */ + def whenMatched(condition: Column): WhenMatched[T] = { + new WhenMatched[T](this, Some(condition.expr)) + } + + /** + * Initialize a `WhenNotMatched` action without any condition. + * + * This `WhenNotMatched` can be followed by one of the following merge actions: + * - `insertAll`: Insert all the target table with source dataset records. + * - `insert(Map)`: Insert all the target table records while changing only + * a subset of fields based on the provided assignment. + * + * @return a new `WhenNotMatched` object. + */ + def whenNotMatched(): WhenNotMatched[T] = { + new WhenNotMatched[T](this, None) + } + + /** + * Initialize a `WhenNotMatched` action with a condition. + * + * This `WhenNotMatched` action will be executed if and only if the specified `condition` + * is satisfied. + * + * This `WhenNotMatched` can be followed by one of the following merge actions: + * - `insertAll`: Insert all the target table with source dataset records. + * - `insert(Map)`: Insert all the target table records while changing only + * a subset of fields based on the provided assignment. + * + * @param condition a `Column` representing the condition to be evaluated for the action. + * @return a new `WhenNotMatched` object configured with the specified condition. + */ + def whenNotMatched(condition: Column): WhenNotMatched[T] = { + new WhenNotMatched[T](this, Some(condition.expr)) + } + + /** + * Initialize a `WhenNotMatchedBySource` action without any condition. + * + * This `WhenNotMatchedBySource` can be followed by one of the following merge actions: + * - `updateAll`: Update all the target table fields with source dataset fields. + * - `update(Map)`: Update all the target table records while changing only + * a subset of fields based on the provided assignment. + * - `delete`: Delete all the target table records. + * + * @return a new `WhenNotMatchedBySource` object. + */ + def whenNotMatchedBySource(): WhenNotMatchedBySource[T] = { + new WhenNotMatchedBySource[T](this, None) + } + + /** + * Initialize a `WhenNotMatchedBySource` action with a condition. + * + * This `WhenNotMatchedBySource` action will be executed if and only if the specified `condition` + * is satisfied. + * + * This `WhenNotMatchedBySource` can be followed by one of the following merge actions: + * - `updateAll`: Update all the target table fields with source dataset fields. + * - `update(Map)`: Update all the target table records while changing only + * a subset of fields based on the provided assignment. + * - `delete`: Delete all the target table records. + * + * @param condition a `Column` representing the condition to be evaluated for the action. + * @return a new `WhenNotMatchedBySource` object configured with the specified condition. + */ + def whenNotMatchedBySource(condition: Column): WhenNotMatchedBySource[T] = { + new WhenNotMatchedBySource[T](this, Some(condition.expr)) + } + + /** + * Executes the merge operation. + */ + def merge(): Unit = { + if (matchedActions.isEmpty && notMatchedActions.isEmpty && notMatchedBySourceActions.isEmpty) { + throw QueryExecutionErrors.mergeIntoAPIError() + } + + val merge = MergeIntoTable( + UnresolvedRelation(tableName), + logicalPlan, + on.get.expr, + matchedActions, + notMatchedActions, + notMatchedBySourceActions) + val qe = sparkSession.sessionState.executePlan(merge) + qe.assertCommandExecuted() + } +} + +/** + * A class for defining actions to be taken when matching rows in a DataFrame during + * an update operation. + * + * @param mergeIntoWriter The MergeIntoWriter instance responsible for writing data to a + * target DataFrame. + * @param condition An optional condition Expression that specifies when the actions + * should be applied. + * If the condition is None, the actions will be applied to all matched + * rows. + * + * @tparam T The type of data in the MergeIntoWriter. + */ +case class WhenMatched[T] (mergeIntoWriter: MergeIntoWriter[T], condition: Option[Expression]) { + /** + * Specifies an action to update all matched rows in the DataFrame. + * + * @return The MergeIntoWriter instance with the update all action configured. + */ + def updateAll(): MergeIntoWriter[T] = { + mergeIntoWriter.matchedActions = mergeIntoWriter.matchedActions :+ UpdateStarAction(condition) Review Comment: I didn't see this last night. 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