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

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

ljfgem commented on code in PR #35636:
URL: https://github.com/apache/spark/pull/35636#discussion_r950735369


##########
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))
+    }
+
+    private def parseViewText(name: String, viewText: String): LogicalPlan = {
+      try {
+        sqlParser.parsePlan(viewText)
+      } catch {
+        case _: ParseException =>
+          throw QueryCompilationErrors.invalidViewText(viewText, name)
+      }
+    }
+
+    /**
+     * Qualify table identifiers with default catalog and namespace if necessary.
+     */
+    private def qualifyTableIdentifiers(
+        child: LogicalPlan,
+        catalogAndNamespace: Seq[String]): LogicalPlan =
+      child transform {
+        case u @ UnresolvedRelation(Seq(table), _, _) =>
+          u.copy(multipartIdentifier = catalogAndNamespace :+ table)
+        case u @ UnresolvedRelation(parts, _, _)
+            if !catalogManager.isCatalogRegistered(parts.head) =>
+          u.copy(multipartIdentifier = catalogAndNamespace.head +: parts)
+      }

Review Comment:
   Hi @jzhuge, I think this implementation assumes that the view and its base tables must share the same catalog? If so, a view catalog must also implement `TableCatalog` interface? 
   Could we add a field like `baseTableCatalogName` in the `View` interface to specify the base tables' catalog, so that the view can be based on tables in another catalog?



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