[SPARK-37636][SQL] Migrate CREATE NAMESPACE to use V2 command by default

sql/core/src/main/scala/org/apache/spark/sql/catalyst/analysis/ResolveSessionCatalog.scala

@@ -214,16 +214,11 @@ class ResolveSessionCatalog(val catalogManager: CatalogManager)
     case DropView(r: ResolvedView, ifExists) =>
       DropTableCommand(r.identifier.asTableIdentifier, ifExists, isView = true, purge = false)
 
-    case c @ CreateNamespace(ResolvedDBObjectName(catalog, name), _, _)
-        if isSessionCatalog(catalog) =>
-      if (name.length != 1) {
-        throw QueryCompilationErrors.invalidDatabaseNameError(name.quoted)
-      }
-
+    case c @ CreateNamespace(DatabaseNameInSessionCatalog(name), _, _) if conf.useV1Command =>
       val comment = c.properties.get(SupportsNamespaces.PROP_COMMENT)
       val location = c.properties.get(SupportsNamespaces.PROP_LOCATION)
       val newProperties = c.properties -- CatalogV2Util.NAMESPACE_RESERVED_PROPERTIES
-      CreateDatabaseCommand(name.head, c.ifNotExists, location, comment, newProperties)
+      CreateDatabaseCommand(name, c.ifNotExists, location, comment, newProperties)
 
     case d @ DropNamespace(DatabaseInSessionCatalog(db), _, _) =>
       DropDatabaseCommand(db, d.ifExists, d.cascade)
@@ -609,4 +604,14 @@ class ResolveSessionCatalog(val catalogManager: CatalogManager)
           resolved.namespace.map(quoteIfNeeded).mkString("."))
     }
   }
+
+  private object DatabaseNameInSessionCatalog {
+    def unapply(resolved: ResolvedDBObjectName): Option[String] = resolved match {
+      case ResolvedDBObjectName(catalog, _) if !isSessionCatalog(catalog) => None
+      case ResolvedDBObjectName(_, Seq(dbName)) => Some(dbName)
+      case _ =>
+        assert(resolved.nameParts.length > 1)
+        throw QueryCompilationErrors.invalidDatabaseNameError(resolved.nameParts.quoted)
+    }
+  }
 }

sql/core/src/test/scala/org/apache/spark/sql/execution/command/CreateNamespaceSuiteBase.scala

@@ -21,7 +21,8 @@ import scala.collection.JavaConverters._
 
 import org.apache.hadoop.fs.Path
 
-import org.apache.spark.sql.{AnalysisException, QueryTest}
+import org.apache.spark.sql.QueryTest
+import org.apache.spark.sql.catalyst.analysis.NamespaceAlreadyExistsException
 import org.apache.spark.sql.catalyst.parser.ParseException
 import org.apache.spark.sql.connector.catalog.{CatalogPlugin, CatalogV2Util, SupportsNamespaces}
 import org.apache.spark.sql.internal.SQLConf
@@ -49,8 +50,6 @@ trait CreateNamespaceSuiteBase extends QueryTest with DDLCommandTestUtils {
 
   protected def notFoundMsgPrefix: String
 
-  protected def alreadyExistErrorMessage: String = s"$notFoundMsgPrefix '$namespace' already exists"
-
   test("basic") {
     val ns = s"$catalog.$namespace"
     withNamespace(ns) {
@@ -88,12 +87,10 @@ trait CreateNamespaceSuiteBase extends QueryTest with DDLCommandTestUtils {
     withNamespace(ns) {
       sql(s"CREATE NAMESPACE $ns")
 
-      // TODO: HiveExternalCatalog throws DatabaseAlreadyExistsException, and
-      //   non-Hive catalogs throw NamespaceAlreadyExistsException.
-      val e = intercept[AnalysisException] {
+      val e = intercept[NamespaceAlreadyExistsException] {
         sql(s"CREATE NAMESPACE $ns")
       }
-      assert(e.getMessage.contains(alreadyExistErrorMessage))
+      assert(e.getMessage.contains(s"$notFoundMsgPrefix '$namespace' already exists"))
 
       // The following will be no-op since the namespace already exists.
       sql(s"CREATE NAMESPACE IF NOT EXISTS $ns")

sql/core/src/test/scala/org/apache/spark/sql/execution/command/TestsV1AndV2Commands.scala

@@ -28,14 +28,21 @@ import org.apache.spark.sql.internal.SQLConf
 trait TestsV1AndV2Commands extends DDLCommandTestUtils {
   private var _version: String = ""
   override def commandVersion: String = _version
+  def runningV1Command: Boolean = commandVersion == "V1"
 
   // Tests using V1 catalogs will run with `spark.sql.legacy.useV1Command` on and off
   // to test both V1 and V2 commands.
   override def test(testName: String, testTags: Tag*)(testFun: => Any)
     (implicit pos: Position): Unit = {
     Seq(true, false).foreach { useV1Command =>
-      _version = if (useV1Command) "V1" else "V2"
+      def setCommandVersion(): Unit = {
+        _version = if (useV1Command) "V1" else "V2"
+      }
+      setCommandVersion()
       super.test(testName, testTags: _*) {
+        // Need to set command version inside this test function so that
+        // the correct command version is available in each test.
+        setCommandVersion()
         withSQLConf(SQLConf.LEGACY_USE_V1_COMMAND.key -> useV1Command.toString) {
           testFun
         }

sql/core/src/test/scala/org/apache/spark/sql/execution/command/v1/CreateNamespaceSuite.scala

@@ -36,7 +36,7 @@ import org.apache.spark.sql.execution.command
 trait CreateNamespaceSuiteBase extends command.CreateNamespaceSuiteBase
     with command.TestsV1AndV2Commands {
   override def namespace: String = "db"
-  override def notFoundMsgPrefix: String = "Database"
+  override def notFoundMsgPrefix: String = if (runningV1Command) "Database" else "Namespace"
 
   test("Create namespace using default warehouse path") {
     val ns = s"$catalog.$namespace"

sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveExternalCatalog.scala

@@ -36,7 +36,7 @@ import org.apache.spark.{SparkConf, SparkException}
 import org.apache.spark.internal.Logging
 import org.apache.spark.sql.AnalysisException
 import org.apache.spark.sql.catalyst.TableIdentifier
-import org.apache.spark.sql.catalyst.analysis.TableAlreadyExistsException
+import org.apache.spark.sql.catalyst.analysis.{DatabaseAlreadyExistsException, TableAlreadyExistsException}
 import org.apache.spark.sql.catalyst.catalog._
 import org.apache.spark.sql.catalyst.catalog.ExternalCatalogUtils._
 import org.apache.spark.sql.catalyst.expressions._
@@ -94,10 +94,22 @@ private[spark] class HiveExternalCatalog(conf: SparkConf, hadoopConf: Configurat
   }
 
   /**
-   * Run some code involving `client` in a [[synchronized]] block and wrap certain
+   * Run some code involving `client` in a [[synchronized]] block and wrap non-fatal
    * exceptions thrown in the process in [[AnalysisException]].
    */
-  private def withClient[T](body: => T): T = synchronized {
+  private def withClient[T](body: => T): T = withClientWrappingException{
+    body
+  } {
+    _ => None // Will fallback to default wrapping strategy in withClientWrappingException.
+  }
+
+  /**
+   * Run some code involving `client` in a [[synchronized]] block and wrap non-fatal
+   * exceptions thrown in the process in [[AnalysisException]] using the given
+   * `wrapException` function.
+   */
+  private def withClientWrappingException[T](body: => T)
+      (wrapException: Throwable => Option[AnalysisException]): T = synchronized {
     try {
       body
     } catch {
@@ -108,8 +120,11 @@ private[spark] class HiveExternalCatalog(conf: SparkConf, hadoopConf: Configurat
           case i: InvocationTargetException => i.getCause
           case o => o
         }
-        throw new AnalysisException(
-          e.getClass.getCanonicalName + ": " + e.getMessage, cause = Some(e))
+        wrapException(e) match {
+          case Some(wrapped) => throw wrapped
+          case None => throw new AnalysisException(
+            e.getClass.getCanonicalName + ": " + e.getMessage, cause = Some(e))
+        }
     }
   }
 
@@ -189,8 +204,17 @@ private[spark] class HiveExternalCatalog(conf: SparkConf, hadoopConf: Configurat
 
   override def createDatabase(
       dbDefinition: CatalogDatabase,
-      ignoreIfExists: Boolean): Unit = withClient {
+      ignoreIfExists: Boolean): Unit = withClientWrappingException {
     client.createDatabase(dbDefinition, ignoreIfExists)
+  } { exception =>
+    if (exception.getClass.getName.equals(
+          "org.apache.hadoop.hive.metastore.api.AlreadyExistsException")
+        && exception.getMessage.contains(
+          s"Database ${dbDefinition.name} already exists")) {
+      Some(new DatabaseAlreadyExistsException(dbDefinition.name))
+    } else {
+      None
+    }
   }
 
   override def dropDatabase(

sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/command/CreateNamespaceSuite.scala

@@ -25,5 +25,4 @@ import org.apache.spark.sql.execution.command.v1
  */
 class CreateNamespaceSuite extends v1.CreateNamespaceSuiteBase with CommandSuiteBase {
   override def commandVersion: String = super[CreateNamespaceSuiteBase].commandVersion
-  override def alreadyExistErrorMessage: String = s"$notFoundMsgPrefix $namespace already exists"
 }