AnishMahto commented on code in PR #56208: URL: https://github.com/apache/spark/pull/56208#discussion_r3336413241
########## sql/pipelines/src/main/scala/org/apache/spark/sql/pipelines/autocdc/Scd2BatchProcessor.scala: ########## @@ -0,0 +1,271 @@ +/* + * 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.pipelines.autocdc + +import org.apache.spark.sql.{functions => F} +import org.apache.spark.sql.Column +import org.apache.spark.sql.catalyst.util.QuotingUtils +import org.apache.spark.sql.classic.DataFrame +import org.apache.spark.sql.types.{DataType, StructType} + +/** + * Per-microbatch processor for SCD Type 2 AutoCDC flows, complying to the specified + * [[changeArgs]] configuration. + * + * @param changeArgs The CDC flow configuration. + * @param resolvedSequencingType The post-analysis [[DataType]] of the sequencing column, derived + * from the flow's resolved DataFrame at flow setup time. + */ +case class Scd2BatchProcessor( + changeArgs: ChangeArgs, + resolvedSequencingType: DataType) { + + /** + * Reconcile a CDC microbatch into the canonical form the auxiliary- and target-table merges + * consume. + * + * Step ordering is load-bearing: the row-extension steps reference user data columns that + * target-column selection is allowed to drop, so selection runs last. Unlike SCD1, no per-key + * deduplication step is needed - SCD2 preserves every event as part of the row's history. Review Comment: Yeah good question, microbatch preprocessing isn't concerned about duplicate/redundant events at all, that will eventually be handled by a downstream step in reconciliation. Updated scaladoc to make it clear! -- 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] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
