Github user gatorsmile commented on a diff in the pull request: https://github.com/apache/spark/pull/16233#discussion_r95305390 --- Diff: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala --- @@ -510,32 +542,90 @@ class Analyzer( * Replaces [[UnresolvedRelation]]s with concrete relations from the catalog. */ object ResolveRelations extends Rule[LogicalPlan] { - private def lookupTableFromCatalog(u: UnresolvedRelation): LogicalPlan = { + + // If the unresolved relation is running directly on files, we just return the original + // UnresolvedRelation, the plan will get resolved later. Else we look up the table from catalog + // and change the default database name if it is a view. + // We usually look up a table from the default database if the table identifier has an empty + // database part, for a view the default database should be the currentDb when the view was + // created. When the case comes to resolving a nested view, the view may have different default + // database with that the referenced view has, so we need to use the variable `defaultDatabase` + // to track the current default database. + // When the relation we resolve is a view, we fetch the view.desc(which is a CatalogTable), and + // then set the value of `CatalogTable.viewDefaultDatabase` to the variable `defaultDatabase`, + // we look up the relations that the view references using the default database. + // For example: + // |- view1 (defaultDatabase = db1) + // |- operator + // |- table2 (defaultDatabase = db1) + // |- view2 (defaultDatabase = db2) + // |- view3 (defaultDatabase = db3) + // |- view4 (defaultDatabase = db4) + // In this case, the view `view1` is a nested view, it directly references `table2`ã`view2` + // and `view4`, the view `view2` references `view3`. On resolving the table, we look up the + // relations `table2`ã`view2`ã`view4` using the default database `db1`, and look up the + // relation `view3` using the default database `db2`. + // + // Note this is compatible with the views defined by older versions of Spark(before 2.2), which + // have empty defaultDatabase and all the relations in viewText have database part defined. + def resolveRelation( + plan: LogicalPlan, + defaultDatabase: Option[String] = None): LogicalPlan = plan match { + case u: UnresolvedRelation if !isRunningDirectlyOnFiles(u.tableIdentifier) => + val defaultDatabase = AnalysisContext.get.defaultDatabase + val relation = lookupTableFromCatalog(u, defaultDatabase) + resolveRelation(relation, defaultDatabase) + // The view's child should be a logical plan parsed from the `desc.viewText`, the variable + // `viewText` should be defined, or else we throw an error on the generation of the View + // operator. + case view @ View(desc, _, child) if !child.resolved => + val nestedViewLevel = AnalysisContext.get.nestedViewLevel + 1 + val context = AnalysisContext(defaultDatabase = desc.viewDefaultDatabase, + nestedViewLevel = nestedViewLevel) + // Resolve all the UnresolvedRelations and Views in the child. + val newChild = AnalysisContext.withAnalysisContext(context) { + execute(child) + } --- End diff -- Like [withWatrmark](https://github.com/apache/spark/blob/master/sql/core/src/main/scala/org/apache/spark/sql/Dataset.scala#L572), we can simplify the above code by changing the interface of `withAnalysisContext`: ```Scala val newChild = AnalysisContext.withAnalysisContext(desc.viewDefaultDatabase) { execute(child) } ``` The `nestedViewLevel` can be incremented by one in `withAnalysisContext`
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