rdblue commented on a change in pull request #24560: [SPARK-27661][SQL] Add SupportsNamespaces API URL: https://github.com/apache/spark/pull/24560#discussion_r307818324
########## File path: sql/catalyst/src/main/java/org/apache/spark/sql/catalog/v2/SupportsNamespaces.java ########## @@ -0,0 +1,145 @@ +/* + * 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.catalyst.analysis.NamespaceAlreadyExistsException; +import org.apache.spark.sql.catalyst.analysis.NoSuchNamespaceException; + +import java.util.Map; + +/** + * Catalog methods for working with namespaces. + * <p> + * If an object such as a table, view, or function exists, its parent namespaces must also exist + * and must be returned by the discovery methods {@link #listNamespaces()} and + * {@link #listNamespaces(String[])}. + * <p> + * Catalog implementations are not required to maintain the existence of namespaces independent of + * objects in a namespace. For example, a function catalog that loads functions using reflection + * and uses Java packages as namespaces is not required to support the methods to create, alter, or + * drop a namespace. Implementations are allowed to discover the existence of objects or namespaces + * without throwing {@link NoSuchNamespaceException} when no namespace is found. + */ +public interface SupportsNamespaces extends CatalogPlugin { + + /** + * Return a default namespace for the catalog. + * <p> + * When this catalog is set as the current catalog, the namespace returned by this method will be + * set as the current namespace. + * <p> + * The namespace returned by this method is not required to exist. + * + * @return a multi-part namespace + */ + default String[] defaultNamespace() { + return new String[0]; + } + + /** + * List top-level namespaces from the catalog. Review comment: Adding to my comment about listing top-level namespaces: if the default namespace changed the catalog's behavior, we would have to document exactly how it should change the behavior and have a way to configure it. I like keeping this simple instead, so these methods do the same thing every time and Spark doesn't require the plugin to maintain a current namespace as state. ---------------------------------------------------------------- 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]
