[GitHub] [spark] jzhuge commented on a diff in pull request #35636: [SPARK-31357][SQL][WIP] Catalog API for view metadata

[GitBox <gi...@apache.org>]

jzhuge commented on code in PR #35636:
URL: https://github.com/apache/spark/pull/35636#discussion_r983105275


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sql/catalyst/src/main/java/org/apache/spark/sql/connector/catalog/ViewCatalog.java:
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@@ -0,0 +1,186 @@
+/*
+ * 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 java.util.Arrays;
+import java.util.List;
+import java.util.Map;
+
+import org.apache.spark.annotation.Experimental;
+import org.apache.spark.sql.catalyst.analysis.NoSuchNamespaceException;
+import org.apache.spark.sql.catalyst.analysis.NoSuchViewException;
+import org.apache.spark.sql.catalyst.analysis.ViewAlreadyExistsException;
+import org.apache.spark.sql.types.StructType;
+
+/**
+ * Catalog methods for working with views.
+ */
+@Experimental
+public interface ViewCatalog extends CatalogPlugin {
+
+  /**
+   * A reserved property to specify the description of the view.
+   */
+  String PROP_COMMENT = "comment";
+
+  /**
+   * A reserved property to specify the owner of the view.
+   */
+  String PROP_OWNER = "owner";
+
+  /**
+   * A reserved property to specify the software version used to create the view.
+   */
+  String PROP_CREATE_ENGINE_VERSION = "create_engine_version";
+
+  /**
+   * A reserved property to specify the software version used to change the view.
+   */
+  String PROP_ENGINE_VERSION = "engine_version";
+
+  /**
+   * All reserved properties of the view.
+   */
+  List<String> RESERVED_PROPERTIES = Arrays.asList(
+        PROP_COMMENT,
+        PROP_OWNER,
+        PROP_CREATE_ENGINE_VERSION,
+        PROP_ENGINE_VERSION);
+
+  /**
+   * List the views in a namespace from the catalog.
+   * <p>
+   * If the catalog supports tables, this must return identifiers for only views and not tables.
+   *
+   * @param namespace a multi-part namespace
+   * @return an array of Identifiers for views
+   * @throws NoSuchNamespaceException If the namespace does not exist (optional).
+   */
+  Identifier[] listViews(String... namespace) throws NoSuchNamespaceException;
+
+  /**
+   * Load view metadata by {@link Identifier ident} from the catalog.
+   * <p>
+   * If the catalog supports tables and contains a table for the identifier and not a view,
+   * this must throw {@link NoSuchViewException}.
+   *
+   * @param ident a view identifier
+   * @return the view description
+   * @throws NoSuchViewException If the view doesn't exist or is a table
+   */
+  View loadView(Identifier ident) throws NoSuchViewException;

Review Comment:
   Similar to these `loadTable` variants? Sure
   ```
     default Table loadTable(Identifier ident, String version)
     default Table loadTable(Identifier ident, long timestamp)
    ```
   
   > Should this API take a list of options (similar to how tables can be queried with a list of options)? For example, I can imagine cases where time travel can be be applied to views (especially with integrating views with other data sources like Iceberg).
   
   



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