rdblue commented on a change in pull request #24246: [SPARK-24252][SQL] Add TableCatalog API URL: https://github.com/apache/spark/pull/24246#discussion_r353863543
########## File path: sql/catalyst/src/main/java/org/apache/spark/sql/catalog/v2/TableCatalog.java ########## @@ -0,0 +1,137 @@ +/* + * 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 org.apache.spark.sql.catalog.v2.expressions.Transform; +import org.apache.spark.sql.catalyst.analysis.NoSuchNamespaceException; +import org.apache.spark.sql.catalyst.analysis.NoSuchTableException; +import org.apache.spark.sql.catalyst.analysis.TableAlreadyExistsException; +import org.apache.spark.sql.sources.v2.Table; +import org.apache.spark.sql.types.StructType; + +import java.util.Map; + +/** + * Catalog methods for working with Tables. + * <p> + * TableCatalog implementations may be case sensitive or case insensitive. Spark will pass + * {@link Identifier table identifiers} without modification. Field names passed to + * {@link #alterTable(Identifier, TableChange...)} will be normalized to match the case used in the + * table schema when updating, renaming, or dropping existing columns when catalyst analysis is case + * insensitive. + */ +public interface TableCatalog extends CatalogPlugin { + /** + * List the tables in a namespace from the catalog. + * <p> + * If the catalog supports views, this must return identifiers for only tables and not views. + * + * @param namespace a multi-part namespace + * @return an array of Identifiers for tables + * @throws NoSuchNamespaceException If the namespace does not exist (optional). + */ + Identifier[] listTables(String[] namespace) throws NoSuchNamespaceException; + + /** + * Load table metadata by {@link Identifier identifier} from the catalog. + * <p> + * If the catalog supports views and contains a view for the identifier and not a table, this + * must throw {@link NoSuchTableException}. + * + * @param ident a table identifier + * @return the table's metadata + * @throws NoSuchTableException If the table doesn't exist or is a view + */ + Table loadTable(Identifier ident) throws NoSuchTableException; + + /** + * Invalidate cached table metadata for an {@link Identifier identifier}. + * <p> + * If the table is already loaded or cached, drop cached data. If the table does not exist or is + * not cached, do nothing. Calling this method should not query remote services. + * + * @param ident a table identifier + */ + default void invalidateTable(Identifier ident) { + } + + /** + * Test whether a table exists using an {@link Identifier identifier} from the catalog. + * <p> + * If the catalog supports views and contains a view for the identifier and not a table, this + * must return false. + * + * @param ident a table identifier + * @return true if the table exists, false otherwise + */ + default boolean tableExists(Identifier ident) { + try { + return loadTable(ident) != null; + } catch (NoSuchTableException e) { + return false; + } + } + + /** + * Create a table in the catalog. + * + * @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) + */ + Table createTable( + Identifier ident, + StructType schema, + Transform[] partitions, + Map<String, String> properties) throws TableAlreadyExistsException, NoSuchNamespaceException; + + /** + * Apply a set of {@link TableChange changes} to a table in the catalog. + * <p> + * Implementations may reject the requested changes. If any change is rejected, none of the + * changes should be applied to the table. + * <p> + * If the catalog supports views and contains a view for the identifier and not a table, this + * must throw {@link NoSuchTableException}. + * + * @param ident a table identifier + * @param changes changes to apply to the table + * @return updated metadata for the table + * @throws NoSuchTableException If the table doesn't exist or is a view + * @throws IllegalArgumentException If any change is rejected by the implementation. + */ + Table alterTable( + Identifier ident, + TableChange... changes) throws NoSuchTableException; + + /** + * Drop a table in the catalog. + * <p> + * If the catalog supports views and contains a view for the identifier and not a table, this + * must not drop the view and must return false. + * + * @param ident a table identifier + * @return true if a table was deleted, false if no table exists for the identifier + */ + boolean dropTable(Identifier ident); Review comment: Purge is an option specific to some sources, like Hive. If you drop a table in most JDBC databases, you don't have an option to keep the data around somewhere. If an option can't be satisfied by sources, then it isn't a good candidate to be in the API. Even in Hive, purge is optional because managed tables will drop data automatically, but external tables will not. Using table configuration for sources that support "external" data is a better option, I think. ---------------------------------------------------------------- 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]
