[GitHub] [flink] xuefuz commented on a change in pull request #8214: [FLINK-11476] [table] Create CatalogManager to manage multiple catalogs and encapsulate Calcite schema

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xuefuz commented on a change in pull request #8214: [FLINK-11476] [table] Create CatalogManager to manage multiple catalogs and encapsulate Calcite schema
URL: https://github.com/apache/flink/pull/8214#discussion_r277833211
 
 

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 File path: flink-table/flink-table-common/src/main/java/org/apache/flink/table/catalog/CatalogManager.java
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+/*
+ * 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.flink.table.catalog;
+
+import org.apache.flink.annotation.PublicEvolving;
+import org.apache.flink.table.api.CatalogAlreadyExistsException;
+import org.apache.flink.table.api.CatalogNotExistException;
+import org.apache.flink.table.catalog.exceptions.DatabaseNotExistException;
+
+import java.util.Set;
+
+/**
+ * CatalogManager manages all the registered ReadableCatalog instances with unique names.
+ * It has a concept of current catalog, which will be used when it is not given when referencing meta-objects.
+ */
+@PublicEvolving
+public interface CatalogManager {
+
+	/**
+	 * Register a catalog with a unique name.
+	 *
+	 * @param catalogName catalog name to register
+	 * @param catalog catalog to register
+	 * @throws CatalogAlreadyExistsException thrown if the name is already take
+	 */
+	void registerCatalog(String catalogName, ReadableCatalog catalog) throws CatalogAlreadyExistsException;
+
+	/**
+	 * Get a catalog by name.
+	 *
+	 * @param catalogName catalog name
+	 * @return the requested catalog
+	 * @throws CatalogNotExistException thrown if the catalog doesn't exist
+	 */
+	ReadableCatalog getCatalog(String catalogName) throws CatalogNotExistException;
+
+	/**
+	 * Get names of all registered catalog.
+	 *
+	 * @return a set of names of registered catalogs
+	 */
+	Set<String> getCatalogNames();
+
+	/**
+	 * Get the current catalog.
+	 *
+	 * @return the current catalog
+	 */
+	ReadableCatalog getCurrentCatalog();
+
+	/**
+	 * Get name of the current database.
+	 *
+	 * @return name of the current database
+	 */
+	String getCurrentDatabaseName();
 
 Review comment:
   At CatalogManager level,  It seems we only need get/setCurrentCatalog() because  get/setCurrentDatabase() are already defined in Catalog API, specifically, in ReadableCatalog class. Thus, we might want to remove getCurrentDatabaseName() and  setCurrentCatalogAndDatabase(), and only keep get/setCurrentCatalog() in CatalogManager.

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