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

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

wmoustafa commented on code in PR #35636:
URL: https://github.com/apache/spark/pull/35636#discussion_r953379100


##########
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala:
##########
@@ -447,6 +454,74 @@ class Analyzer(override val catalogManager: CatalogManager)
     }
   }
 
+  /**
+   * Substitute persisted views in parsed plans with parsed view sql text.
+   */
+  case class ViewSubstitution(sqlParser: ParserInterface) extends Rule[LogicalPlan] {
+
+    def apply(plan: LogicalPlan): LogicalPlan = plan.resolveOperatorsUp {
+      case u @ UnresolvedRelation(nameParts, _, _) if v1SessionCatalog.isTempView(nameParts) =>
+        u
+      case u @ UnresolvedRelation(
+          parts @ NonSessionCatalogAndIdentifier(catalog, ident), _, _) if !isSQLOnFile(parts) =>
+        CatalogV2Util.loadView(catalog, ident)
+            .map(createViewRelation(parts.quoted, _))
+            .getOrElse(u)
+    }
+
+    private def isSQLOnFile(parts: Seq[String]): Boolean = parts match {
+      case Seq(_, path) if path.contains("/") => true
+      case _ => false
+    }
+
+    private def createViewRelation(name: String, view: V2View): LogicalPlan = {
+      if (!catalogManager.isCatalogRegistered(view.currentCatalog)) {
+        throw new AnalysisException(
+          s"Invalid current catalog '${view.currentCatalog}' in view '$name'")
+      }
+
+      val child = parseViewText(name, view.sql)
+      val desc = V2ViewDescription(name, view)
+      val qualifiedChild = desc.viewCatalogAndNamespace match {
+        case Seq() =>
+          // Views from Spark 2.2 or prior do not store catalog or namespace,
+          // however its sql text should already be fully qualified.
+          child
+        case catalogAndNamespace =>
+          // Substitute CTEs within the view before qualifying table identifiers
+          qualifyTableIdentifiers(CTESubstitution.apply(child), catalogAndNamespace)
+      }
+
+      // The relation is a view, so we wrap the relation by:
+      // 1. Add a [[View]] operator over the relation to keep track of the view desc;
+      // 2. Wrap the logical plan in a [[SubqueryAlias]] which tracks the name of the view.
+      SubqueryAlias(name, View(desc, false, qualifiedChild))

Review Comment:
   I think we should add this node for two reasons:
   (1) For feature parity with the built-in Hive external catalog implementation.
   (2) We have seen cases where merely resolving view based on text loses some casing and nullability information of underlying tables.
   This project node should leverage the `schema()` method of the `View` API.



##########
sql/catalyst/src/main/java/org/apache/spark/sql/connector/catalog/ViewCatalog.java:
##########
@@ -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:
   Should this API take a list 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).



-- 
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.

To unsubscribe, e-mail: reviews-unsubscribe@spark.apache.org

For queries about this service, please contact Infrastructure at:
users@infra.apache.org


---------------------------------------------------------------------
To unsubscribe, e-mail: reviews-unsubscribe@spark.apache.org
For additional commands, e-mail: reviews-help@spark.apache.org