Github user twalthr commented on a diff in the pull request:
https://github.com/apache/flink/pull/3406#discussion_r106346971
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/catalog/CrudExternalCatalog.scala
---
@@ -0,0 +1,110 @@
+/*
+ * 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.table.api._
+
+/**
+ * This class is responsible for interact with external catalog.
+ * Its main responsibilities including:
+ * <ul>
+ * <li> create/drop/alter database or tables for DDL operations
+ * <li> provide tables for calcite catalog, it looks up databases or
tables in the external catalog
+ * </ul>
+ */
+trait CrudExternalCatalog extends ExternalCatalog {
+
+ /**
+ * Adds table into external Catalog
+ *
+ * @param table description of table which to create
+ * @param ignoreIfExists if table already exists in the catalog, not
throw exception and leave
+ * the existed table if ignoreIfExists is true;
+ * else throw a TableAlreadyExistException.
+ * @throws DatabaseNotExistException if database does not exist in the
catalog yet
+ * @throws TableAlreadyExistException if table already exists in the
catalog and
+ * ignoreIfExists is false
+ */
+ @throws[DatabaseNotExistException]
+ @throws[TableAlreadyExistException]
+ def createTable(table: ExternalCatalogTable, ignoreIfExists: Boolean):
Unit
+
+ /**
+ * Deletes table from external Catalog
+ *
+ * @param dbName database name
+ * @param tableName table name
+ * @param ignoreIfNotExists if table not exist yet, not throw exception
if ignoreIfNotExists is
+ * true; else throw TableNotExistException
+ * @throws DatabaseNotExistException if database does not exist in the
catalog yet
+ * @throws TableNotExistException if table does not exist in the
catalog yet
+ */
+ @throws[DatabaseNotExistException]
+ @throws[TableNotExistException]
+ def dropTable(dbName: String, tableName: String, ignoreIfNotExists:
Boolean): Unit
--- End diff --
Why is a database name necessary for dropping but not for creating or
altering?
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