brkyvz 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_r302750267
########## 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 + * {@link BatchWrite#commit(WriterCommitMessage[])} is called, + * {@link StagedTable#commitStagedChanges()} is called, at which point the staged table can + * complete both the data write and the metadata swap operation atomically. + */ +public interface StagingTableCatalog extends TableCatalog { + + /** + * Stage the creation of a table, preparing it to be committed into the metastore. + * <p> + * When the table is committed, the contents of any writes performed by the Spark planner are + * committed along with the metadata about the table passed into this method's arguments. If the + * table exists when this method is called, the method should throw an exception accordingly. If + * another process concurrently creates the table before this table's staged changes are + * committed, an exception should be thrown by {@link StagedTable#commitStagedChanges()}. + * + * @param ident a table identifier + * @param schema the schema of the new table, as a struct type + * @param partitions transforms to use for partitioning data in the table + * @param properties a string map of table properties + * @return metadata for the new table + * @throws TableAlreadyExistsException If a table or view already exists for the identifier + * @throws UnsupportedOperationException If a requested partition transform is not supported + * @throws NoSuchNamespaceException If the identifier namespace does not exist (optional) + */ + StagedTable stageCreate( + Identifier ident, + StructType schema, + Transform[] partitions, + Map<String, String> properties) throws TableAlreadyExistsException, NoSuchNamespaceException; + ; Review comment: spurious `;`? ---------------------------------------------------------------- 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: [email protected] With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
