cloud-fan commented on code in PR #53215: URL: https://github.com/apache/spark/pull/53215#discussion_r2562476950
########## sql/catalyst/src/main/java/org/apache/spark/sql/connector/catalog/RequiresDataFrameWriterV1SaveAsTableOverwriteWriteOption.java: ########## @@ -0,0 +1,63 @@ +/* + * 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.catalog; + +import org.apache.spark.annotation.Evolving; + +/** + * A marker interface that can be mixed into a {@link TableProvider} to indicate that the data + * source needs to distinguish between DataFrameWriter V1 {@code saveAsTable} operations and + * DataFrameWriter V2 {@code createOrReplace}/{@code replace} operations. + * <p> + * Background: DataFrameWriter V1's {@code saveAsTable} with {@code SaveMode.Overwrite} creates + * a {@code ReplaceTableAsSelect} logical plan, which is identical to the plan created by + * DataFrameWriter V2's {@code createOrReplace}. However, the documented semantics can have + * different interpretations: + * <ul> + * <li>V1 saveAsTable with Overwrite: "if data/table already exists, existing data is expected + * to be overwritten by the contents of the DataFrame" - does not define behavior for + * metadata (schema) overwriting</li> + * <li>V2 createOrReplace: "The output table's schema, partition layout, properties, and other + * configuration will be based on the contents of the data frame... If the table exists, + * its configuration and data will be replaced"</li> + * </ul> + * <p> + * Data sources that migrated from V1 to V2 may have adopted different behaviors based on these + * documented semantics. For example, Delta Lake interprets V1 saveAsTable to not replace table + * schema unless the {@code overwriteSchema} option is explicitly set. + * <p> + * When a {@link TableProvider} implements this interface, DataFrameWriter V1 will add an + * internal write option to indicate that the command originated from V1 saveAsTable API. + * This allows the data source to distinguish between the two APIs and apply appropriate + * semantics. + * <p> + * The option key used is defined by + * {@link #IS_DATAFRAME_WRITER_V1_SAVE_AS_TABLE_OVERWRITE_OPTION_NAME} + * and the value will be "true" when the write originates from DataFrameWriter V1. + * + * @since 4.1.0 + */ +@Evolving +public interface RequiresDataFrameWriterV1SaveAsTableOverwriteWriteOption extends TableProvider { Review Comment: In general we should avoid marker interfaces, as they are static at compile time and implementation can't dynamically choose true or false. For this case, we probably don't need it to be dynamic as it doesn't hurt to add one extra write option, so I'm fine with it. -- 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]
