rdblue commented on a change in pull request #24798: [SPARK-27724][SQL] Implement REPLACE TABLE and REPLACE TABLE AS SELECT with V2 URL: https://github.com/apache/spark/pull/24798#discussion_r294466468
########## File path: sql/catalyst/src/main/java/org/apache/spark/sql/catalog/v2/StagingTableCatalog.java ########## @@ -0,0 +1,105 @@ +/* + * 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.catalog.v2; + +import java.util.Map; + +import org.apache.spark.sql.catalog.v2.expressions.Transform; +import org.apache.spark.sql.catalyst.analysis.NoSuchNamespaceException; +import org.apache.spark.sql.catalyst.analysis.TableAlreadyExistsException; +import org.apache.spark.sql.sources.v2.StagedTable; +import org.apache.spark.sql.sources.v2.SupportsWrite; +import org.apache.spark.sql.sources.v2.writer.BatchWrite; +import org.apache.spark.sql.sources.v2.writer.WriterCommitMessage; +import org.apache.spark.sql.types.StructType; +import org.apache.spark.sql.util.CaseInsensitiveStringMap; + +/** + * An optional mix-in for implementations of {@link TableCatalog} that support staging creation of + * the a table before committing the table's metadata along with its contents in CREATE TABLE AS + * SELECT or REPLACE TABLE AS SELECT operations. + * <p> + * It is highly recommended to implement this trait whenever possible so that CREATE TABLE AS + * SELECT and REPLACE TABLE AS SELECT operations are atomic. For example, when one runs a REPLACE + * TABLE AS SELECT operation, if the catalog does not implement this trait, the planner will first + * drop the table via {@link TableCatalog#dropTable(Identifier)}, then create the table via + * {@link TableCatalog#createTable(Identifier, StructType, Transform[], Map)}, and then perform + * the write via {@link SupportsWrite#newWriteBuilder(CaseInsensitiveStringMap)}. However, if the + * write operation fails, the catalog will have already dropped the table, and the planner cannot + * roll back the dropping of the table. + * <p> + * If the catalog implements this plugin, the catalog can implement the methods to "stage" the + * creation and the replacement of a table. After the table's Review comment: Looks like this doc is unfinished. ---------------------------------------------------------------- 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. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For additional commands, e-mail: reviews-h...@spark.apache.org
