[SPARK-30214][SQL][FOLLOWUP] Remove statement logical plans for namespace commands

### What changes were proposed in this pull request?

This is a follow-up to address the following comment: #27095 (comment)

Currently, a SQL command string is parsed to a "statement" logical plan, converted to a logical plan with catalog/namespace, then finally converted to a physical plan. With the new resolution framework, there is no need to create a "statement" logical plan; a logical plan can contain `UnresolvedNamespace` which will be resolved to a `ResolvedNamespace`. This should simply the code base and make it a bit easier to add a new command.

### Why are the changes needed?

Clean up codebase.

### Does this PR introduce any user-facing change?

No

### How was this patch tested?

Existing tests should cover the changes.

Closes #27125 from imback82/SPARK-30214-followup.

Authored-by: Terry Kim <yuminkim@gmail.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>

Author: imback82

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala

@@ -730,7 +730,7 @@ class Analyzer(
   case class ResolveNamespace(catalogManager: CatalogManager)
     extends Rule[LogicalPlan] with LookupCatalog {
     def apply(plan: LogicalPlan): LogicalPlan = plan resolveOperators {
-      case s @ ShowTablesStatement(UnresolvedNamespace(Seq()), _) =>
+      case s @ ShowTables(UnresolvedNamespace(Seq()), _) =>
         s.copy(namespace =
           ResolvedNamespace(currentCatalog.asNamespaceCatalog, catalogManager.currentNamespace))
       case UnresolvedNamespace(Seq()) =>

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/ResolveCatalogs.scala

@@ -106,15 +106,6 @@ class ResolveCatalogs(val catalogManager: CatalogManager)
         s"Can not specify catalog `${catalog.name}` for view ${tbl.quoted} " +
           s"because view support in catalog has not been implemented yet")
 
-    case AlterNamespaceSetPropertiesStatement(
-        NonSessionCatalogAndNamespace(catalog, ns), properties) =>
-      AlterNamespaceSetProperties(catalog, ns, properties)
-
-    case AlterNamespaceSetLocationStatement(
-        NonSessionCatalogAndNamespace(catalog, ns), location) =>
-      AlterNamespaceSetProperties(catalog, ns,
-        Map(SupportsNamespaces.PROP_LOCATION -> location))
-
     case RenameTableStatement(NonSessionCatalogAndTable(catalog, oldName), newNameParts, isView) =>
       if (isView) {
         throw new AnalysisException("Renaming view is not supported in v2 catalogs.")
@@ -194,18 +185,6 @@ class ResolveCatalogs(val catalogManager: CatalogManager)
         if !isSessionCatalog(catalog) =>
       CreateNamespace(catalog.asNamespaceCatalog, ns, c.ifNotExists, c.properties)
 
-    case DropNamespaceStatement(NonSessionCatalogAndNamespace(catalog, ns), ifExists, cascade) =>
-      DropNamespace(catalog, ns, ifExists, cascade)
-
-    case DescribeNamespaceStatement(NonSessionCatalogAndNamespace(catalog, ns), extended) =>
-      DescribeNamespace(catalog, ns, extended)
-
-    case ShowNamespacesStatement(NonSessionCatalogAndNamespace(catalog, ns), pattern) =>
-      ShowNamespaces(catalog, ns, pattern)
-
-    case ShowTablesStatement(NonSessionCatalogAndNamespace(catalog, ns), pattern) =>
-      ShowTables(catalog.asTableCatalog, ns, pattern)
-
     case UseStatement(isNamespaceSet, nameParts) =>
       if (isNamespaceSet) {
         SetCatalogAndNamespace(catalogManager, None, Some(nameParts))
@@ -231,13 +210,4 @@ class ResolveCatalogs(val catalogManager: CatalogManager)
       case _ => None
     }
   }
-
-  object NonSessionCatalogAndNamespace {
-    def unapply(resolved: ResolvedNamespace): Option[(SupportsNamespaces, Seq[String])] =
-      if (!isSessionCatalog(resolved.catalog)) {
-        Some(resolved.catalog -> resolved.namespace)
-      } else {
-        None
-      }
-  }
 }

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/parser/AstBuilder.scala

@@ -2563,22 +2563,22 @@ class AstBuilder(conf: SQLConf) extends SqlBaseBaseVisitor[AnyRef] with Logging
   }
 
   /**
-   * Create a [[DropNamespaceStatement]] command.
+   * Create a [[DropNamespace]] command.
    *
    * For example:
    * {{{
    *   DROP (DATABASE|SCHEMA|NAMESPACE) [IF EXISTS] ns1.ns2 [RESTRICT|CASCADE];
    * }}}
    */
   override def visitDropNamespace(ctx: DropNamespaceContext): LogicalPlan = withOrigin(ctx) {
-    DropNamespaceStatement(
+    DropNamespace(
       UnresolvedNamespace(visitMultipartIdentifier(ctx.multipartIdentifier)),
       ctx.EXISTS != null,
       ctx.CASCADE != null)
   }
 
   /**
-   * Create an [[AlterNamespaceSetPropertiesStatement]] logical plan.
+   * Create an [[AlterNamespaceSetProperties]] logical plan.
    *
    * For example:
    * {{{
@@ -2588,14 +2588,14 @@ class AstBuilder(conf: SQLConf) extends SqlBaseBaseVisitor[AnyRef] with Logging
    */
   override def visitSetNamespaceProperties(ctx: SetNamespacePropertiesContext): LogicalPlan = {
     withOrigin(ctx) {
-      AlterNamespaceSetPropertiesStatement(
+      AlterNamespaceSetProperties(
         UnresolvedNamespace(visitMultipartIdentifier(ctx.multipartIdentifier)),
         visitPropertyKeyValues(ctx.tablePropertyList))
     }
   }
 
   /**
-   * Create an [[AlterNamespaceSetLocationStatement]] logical plan.
+   * Create an [[AlterNamespaceSetLocation]] logical plan.
    *
    * For example:
    * {{{
@@ -2604,28 +2604,28 @@ class AstBuilder(conf: SQLConf) extends SqlBaseBaseVisitor[AnyRef] with Logging
    */
   override def visitSetNamespaceLocation(ctx: SetNamespaceLocationContext): LogicalPlan = {
     withOrigin(ctx) {
-      AlterNamespaceSetLocationStatement(
+      AlterNamespaceSetLocation(
         UnresolvedNamespace(visitMultipartIdentifier(ctx.multipartIdentifier)),
         visitLocationSpec(ctx.locationSpec))
     }
   }
 
   /**
-   * Create a [[ShowNamespacesStatement]] command.
+   * Create a [[ShowNamespaces]] command.
    */
   override def visitShowNamespaces(ctx: ShowNamespacesContext): LogicalPlan = withOrigin(ctx) {
     if (ctx.DATABASES != null && ctx.multipartIdentifier != null) {
       throw new ParseException(s"FROM/IN operator is not allowed in SHOW DATABASES", ctx)
     }
 
     val multiPart = Option(ctx.multipartIdentifier).map(visitMultipartIdentifier)
-    ShowNamespacesStatement(
+    ShowNamespaces(
       UnresolvedNamespace(multiPart.getOrElse(Seq.empty[String])),
       Option(ctx.pattern).map(string))
   }
 
   /**
-   * Create a [[DescribeNamespaceStatement]].
+   * Create a [[DescribeNamespace]].
    *
    * For example:
    * {{{
@@ -2634,7 +2634,7 @@ class AstBuilder(conf: SQLConf) extends SqlBaseBaseVisitor[AnyRef] with Logging
    */
   override def visitDescribeNamespace(ctx: DescribeNamespaceContext): LogicalPlan =
     withOrigin(ctx) {
-      DescribeNamespaceStatement(
+      DescribeNamespace(
         UnresolvedNamespace(visitMultipartIdentifier(ctx.multipartIdentifier())),
         ctx.EXTENDED != null)
     }
@@ -2802,11 +2802,11 @@ class AstBuilder(conf: SQLConf) extends SqlBaseBaseVisitor[AnyRef] with Logging
   }
 
   /**
-   * Create a [[ShowTablesStatement]] command.
+   * Create a [[ShowTables]] command.
    */
   override def visitShowTables(ctx: ShowTablesContext): LogicalPlan = withOrigin(ctx) {
     val multiPart = Option(ctx.multipartIdentifier).map(visitMultipartIdentifier)
-    ShowTablesStatement(
+    ShowTables(
       UnresolvedNamespace(multiPart.getOrElse(Seq.empty[String])),
       Option(ctx.pattern).map(string))
   }

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/statements.scala

@@ -298,15 +298,6 @@ case class DescribeTableStatement(
     partitionSpec: TablePartitionSpec,
     isExtended: Boolean) extends ParsedStatement
 
-/**
- * A DESCRIBE NAMESPACE statement, as parsed from SQL.
- */
-case class DescribeNamespaceStatement(
-    namespace: LogicalPlan,
-    extended: Boolean) extends ParsedStatement {
-  override def children: Seq[LogicalPlan] = Seq(namespace)
-}
-
 /**
  * A DESCRIBE TABLE tbl_name col_name statement, as parsed from SQL.
  */
@@ -345,15 +336,6 @@ case class InsertIntoStatement(
   override def children: Seq[LogicalPlan] = query :: Nil
 }
 
-/**
- * A SHOW TABLES statement, as parsed from SQL.
- */
-case class ShowTablesStatement(
-    namespace: LogicalPlan,
-    pattern: Option[String]) extends ParsedStatement {
-  override def children: Seq[LogicalPlan] = Seq(namespace)
-}
-
 /**
  * A SHOW TABLE EXTENDED statement, as parsed from SQL.
  */
@@ -371,43 +353,6 @@ case class CreateNamespaceStatement(
     ifNotExists: Boolean,
     properties: Map[String, String]) extends ParsedStatement
 
-/**
- * A DROP NAMESPACE statement, as parsed from SQL.
- */
-case class DropNamespaceStatement(
-    namespace: LogicalPlan,
-    ifExists: Boolean,
-    cascade: Boolean) extends ParsedStatement {
-  override def children: Seq[LogicalPlan] = Seq(namespace)
-}
-
-/**
- * ALTER (DATABASE|SCHEMA|NAMESPACE) ... SET (DBPROPERTIES|PROPERTIES) command, as parsed from SQL.
- */
-case class AlterNamespaceSetPropertiesStatement(
-    namespace: LogicalPlan,
-    properties: Map[String, String]) extends ParsedStatement {
-  override def children: Seq[LogicalPlan] = Seq(namespace)
-}
-
-/**
- * ALTER (DATABASE|SCHEMA|NAMESPACE) ... SET LOCATION command, as parsed from SQL.
- */
-case class AlterNamespaceSetLocationStatement(
-    namespace: LogicalPlan,
-    location: String) extends ParsedStatement {
-  override def children: Seq[LogicalPlan] = Seq(namespace)
-}
-
-/**
- * A SHOW NAMESPACES statement, as parsed from SQL.
- */
-case class ShowNamespacesStatement(
-    namespace: LogicalPlan,
-    pattern: Option[String]) extends ParsedStatement {
-  override def children: Seq[LogicalPlan] = Seq(namespace)
-}
-
 /**
  * A USE statement, as parsed from SQL.
  */

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/v2Commands.scala

@@ -250,18 +250,19 @@ case class CreateNamespace(
  * The logical plan of the DROP NAMESPACE command that works for v2 catalogs.
  */
 case class DropNamespace(
-    catalog: CatalogPlugin,
-    namespace: Seq[String],
+    namespace: LogicalPlan,
     ifExists: Boolean,
-    cascade: Boolean) extends Command
+    cascade: Boolean) extends Command {
+  override def children: Seq[LogicalPlan] = Seq(namespace)
+}
 
 /**
  * The logical plan of the DESCRIBE NAMESPACE command that works for v2 catalogs.
  */
 case class DescribeNamespace(
-    catalog: SupportsNamespaces,
-    namespace: Seq[String],
+    namespace: LogicalPlan,
     extended: Boolean) extends Command {
+  override def children: Seq[LogicalPlan] = Seq(namespace)
 
   override def output: Seq[Attribute] = Seq(
     AttributeReference("name", StringType, nullable = false,
@@ -275,17 +276,29 @@ case class DescribeNamespace(
  * command that works for v2 catalogs.
  */
 case class AlterNamespaceSetProperties(
-    catalog: SupportsNamespaces,
-    namespace: Seq[String],
-    properties: Map[String, String]) extends Command
+    namespace: LogicalPlan,
+    properties: Map[String, String]) extends Command {
+  override def children: Seq[LogicalPlan] = Seq(namespace)
+}
+
+/**
+ * The logical plan of the ALTER (DATABASE|SCHEMA|NAMESPACE) ... SET LOCATION
+ * command that works for v2 catalogs.
+ */
+case class AlterNamespaceSetLocation(
+    namespace: LogicalPlan,
+    location: String) extends Command {
+  override def children: Seq[LogicalPlan] = Seq(namespace)
+}
 
 /**
  * The logical plan of the SHOW NAMESPACES command that works for v2 catalogs.
  */
 case class ShowNamespaces(
-    catalog: SupportsNamespaces,
-    namespace: Seq[String],
+    namespace: LogicalPlan,
     pattern: Option[String]) extends Command {
+  override def children: Seq[LogicalPlan] = Seq(namespace)
+
   override val output: Seq[Attribute] = Seq(
     AttributeReference("namespace", StringType, nullable = false)())
 }
@@ -412,9 +425,10 @@ case class RenameTable(
  * The logical plan of the SHOW TABLE command that works for v2 catalogs.
  */
 case class ShowTables(
-    catalog: TableCatalog,
-    namespace: Seq[String],
+    namespace: LogicalPlan,
     pattern: Option[String]) extends Command {
+  override def children: Seq[LogicalPlan] = Seq(namespace)
+
   override val output: Seq[Attribute] = Seq(
     AttributeReference("namespace", StringType, nullable = false)(),
     AttributeReference("tableName", StringType, nullable = false)())