[SPARK-14177][SQL] Native Parsing for DDL Command "Describe Database" and "Alter Database"

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

This PR is to provide native parsing support for two DDL commands:  ```Describe Database``` and ```Alter Database Set Properties```

Based on the Hive DDL document:
https://cwiki.apache.org/confluence/display/Hive/LanguageManual+DDL

##### 1. ALTER DATABASE
**Syntax:**
```SQL
ALTER (DATABASE|SCHEMA) database_name SET DBPROPERTIES (property_name=property_value, ...)
```
 - `ALTER DATABASE` is to add new (key, value) pairs into `DBPROPERTIES`

##### 2. DESCRIBE DATABASE
**Syntax:**
```SQL
DESCRIBE DATABASE [EXTENDED] db_name
```
 - `DESCRIBE DATABASE` shows the name of the database, its comment (if one has been set), and its root location on the filesystem. When `extended` is true, it also shows the database's properties

#### How was this patch tested?
Added the related test cases to `DDLCommandSuite`

Author: gatorsmile <gatorsmile@gmail.com>
Author: xiaoli <lixiao1983@gmail.com>
Author: Xiao Li <xiaoli@Xiaos-MacBook-Pro.local>

This patch had conflicts when merged, resolved by
Committer: Yin Huai <yhuai@databricks.com>

Closes #11977 from gatorsmile/parseAlterDatabase.

4 files changed, 80 insertions, 3 deletions

diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/SparkQl.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/SparkQl.scala
index c78b9b429c..d4d1992d27 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/SparkQl.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/SparkQl.scala
@@ -142,6 +142,33 @@ private[sql] class SparkQl(conf: ParserConf = SimpleParserConf()) extends Cataly
           "TOK_IFEXISTS", "TOK_RESTRICT", "TOK_CASCADE"), otherArgs)
         DropDatabase(databaseName, ifExists.isDefined, restrict = cascade.isEmpty)(node.source)
 
+      // ALTER (DATABASE|SCHEMA) database_name SET DBPROPERTIES (property_name=property_value, ...)
+      case Token("TOK_ALTERDATABASE_PROPERTIES", Token(dbName, Nil) :: args) =>
+        val databaseName = unquoteString(dbName)
+        val dbprops = getClause("TOK_DATABASEPROPERTIES", args)
+        val props = dbprops match {
+          case Token("TOK_DATABASEPROPERTIES", Token("TOK_DBPROPLIST", propList) :: Nil) =>
+            // Example format:
+            //
+            //   TOK_DATABASEPROPERTIES
+            //   +- TOK_DBPROPLIST
+            //      :- TOK_TABLEPROPERTY
+            //      :  :- 'k1'
+            //      :  +- 'v1'
+            //      :- TOK_TABLEPROPERTY
+            //         :- 'k2'
+            //         +- 'v2'
+            extractProps(propList, "TOK_TABLEPROPERTY")
+          case _ => parseFailed("Invalid ALTER DATABASE command", node)
+        }
+        AlterDatabaseProperties(databaseName, props.toMap)(node.source)
+
+      // DESCRIBE DATABASE [EXTENDED] db_name
+      case Token("TOK_DESCDATABASE", Token(dbName, Nil) :: describeArgs) =>
+        val databaseName = unquoteString(dbName)
+        val extended = getClauseOption("EXTENDED", describeArgs)
+        DescribeDatabase(databaseName, extended.isDefined)(node.source)
+
       // CREATE [TEMPORARY] FUNCTION [db_name.]function_name AS class_name
       // [USING JAR|FILE|ARCHIVE 'file_uri' [, JAR|FILE|ARCHIVE 'file_uri'] ];
       case Token("TOK_CREATEFUNCTION", args) =>
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/command/ddl.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/command/ddl.scala
index a0f5b75284..0e51abb44b 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/command/ddl.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/command/ddl.scala
@@ -71,6 +71,21 @@ case class DropDatabase(
     restrict: Boolean)(sql: String)
   extends NativeDDLCommand(sql) with Logging
 
+/** ALTER DATABASE: add new (key, value) pairs into DBPROPERTIES */
+case class AlterDatabaseProperties(
+    databaseName: String,
+    props: Map[String, String])(sql: String)
+  extends NativeDDLCommand(sql) with Logging
+
+/**
+ * DESCRIBE DATABASE: shows the name of the database, its comment (if one has been set), and its
+ * root location on the filesystem. When extended is true, it also shows the database's properties
+ */
+case class DescribeDatabase(
+    databaseName: String,
+    extended: Boolean)(sql: String)
+  extends NativeDDLCommand(sql) with Logging
+
 case class CreateFunction(
     databaseName: Option[String],
     functionName: String,
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/DDLCommandSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/DDLCommandSuite.scala
index 18f48ffa94..7a6343748b 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/DDLCommandSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/DDLCommandSuite.scala
@@ -101,6 +101,44 @@ class DDLCommandSuite extends PlanTest {
     comparePlans(parsed7, expected7)
   }
 
+  test("alter database set dbproperties") {
+    // ALTER (DATABASE|SCHEMA) database_name SET DBPROPERTIES (property_name=property_value, ...)
+    val sql1 = "ALTER DATABASE database_name SET DBPROPERTIES ('a'='a', 'b'='b', 'c'='c')"
+    val sql2 = "ALTER SCHEMA database_name SET DBPROPERTIES ('a'='a')"
+
+    val parsed1 = parser.parsePlan(sql1)
+    val parsed2 = parser.parsePlan(sql2)
+
+    val expected1 = AlterDatabaseProperties(
+      "database_name",
+      Map("a" -> "a", "b" -> "b", "c" -> "c"))(sql1)
+    val expected2 = AlterDatabaseProperties(
+      "database_name",
+      Map("a" -> "a"))(sql2)
+
+    comparePlans(parsed1, expected1)
+    comparePlans(parsed2, expected2)
+  }
+
+  test("describe database") {
+    // DESCRIBE DATABASE [EXTENDED] db_name;
+    val sql1 = "DESCRIBE DATABASE EXTENDED db_name"
+    val sql2 = "DESCRIBE DATABASE db_name"
+
+    val parsed1 = parser.parsePlan(sql1)
+    val parsed2 = parser.parsePlan(sql2)
+
+    val expected1 = DescribeDatabase(
+      "db_name",
+      extended = true)(sql1)
+    val expected2 = DescribeDatabase(
+      "db_name",
+      extended = false)(sql2)
+
+    comparePlans(parsed1, expected1)
+    comparePlans(parsed2, expected2)
+  }
+
   test("create function") {
     val sql1 =
       """
diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveQl.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveQl.scala
index 61fe0985c1..e5bcb9b1db 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveQl.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveQl.scala
@@ -85,7 +85,6 @@ private[hive] class HiveQl(conf: ParserConf) extends SparkQl(conf) with Logging
 
   protected val nativeCommands = Seq(
     "TOK_ALTERDATABASE_OWNER",
-    "TOK_ALTERDATABASE_PROPERTIES",
     "TOK_ALTERINDEX_PROPERTIES",
     "TOK_ALTERINDEX_REBUILD",
     "TOK_ALTERTABLE_ALTERPARTS",
@@ -100,8 +99,6 @@ private[hive] class HiveQl(conf: ParserConf) extends SparkQl(conf) with Logging
     "TOK_CREATEMACRO",
     "TOK_CREATEROLE",
 
-    "TOK_DESCDATABASE",
-
     "TOK_DROPINDEX",
     "TOK_DROPMACRO",
     "TOK_DROPROLE",