[SPARK-14348][SQL] Support native execution of SHOW TBLPROPERTIES command

## What changes were proposed in this pull request?

This PR adds Native execution of SHOW TBLPROPERTIES command.

Command Syntax:
``` SQL
SHOW TBLPROPERTIES table_name[(property_key_literal)]
```
## How was this patch tested?

Tests added in HiveComandSuiie and DDLCommandSuite

Author: Dilip Biswal <dbiswal@us.ibm.com>

Closes #12133 from dilipbiswal/dkb_show_tblproperties.

3 files changed, 81 insertions, 8 deletions

diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/SparkSqlParser.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/SparkSqlParser.scala
index ff3ab7746c..fb106d1aef 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/SparkSqlParser.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/SparkSqlParser.scala
@@ -93,6 +93,22 @@ class SparkSqlAstBuilder extends AstBuilder {
   }
 
   /**
+   * A command for users to list the properties for a table. If propertyKey is specified, the value
+   * for the propertyKey is returned. If propertyKey is not specified, all the keys and their
+   * corresponding values are returned.
+   * The syntax of using this command in SQL is:
+   * {{{
+   *   SHOW TBLPROPERTIES table_name[('propertyKey')];
+   * }}}
+   */
+  override def visitShowTblProperties(
+      ctx: ShowTblPropertiesContext): LogicalPlan = withOrigin(ctx) {
+    ShowTablePropertiesCommand(
+      visitTableIdentifier(ctx.tableIdentifier),
+      Option(ctx.key).map(visitTablePropertyKey))
+  }
+
+  /**
    * Create a [[RefreshTable]] logical plan.
    */
   override def visitRefreshTable(ctx: RefreshTableContext): LogicalPlan = withOrigin(ctx) {
@@ -220,19 +236,26 @@ class SparkSqlAstBuilder extends AstBuilder {
   override def visitTablePropertyList(
       ctx: TablePropertyListContext): Map[String, String] = withOrigin(ctx) {
     ctx.tableProperty.asScala.map { property =>
-      // A key can either be a String or a collection of dot separated elements. We need to treat
-      // these differently.
-      val key = if (property.key.STRING != null) {
-        string(property.key.STRING)
-      } else {
-        property.key.getText
-      }
+      val key = visitTablePropertyKey(property.key)
       val value = Option(property.value).map(string).orNull
       key -> value
     }.toMap
   }
 
   /**
+   * A table property key can either be String or a collection of dot separated elements. This
+   * function extracts the property key based on whether its a string literal or a table property
+   * identifier.
+   */
+  override def visitTablePropertyKey(key: TablePropertyKeyContext): String = {
+    if (key.STRING != null) {
+      string(key.STRING)
+    } else {
+      key.getText
+    }
+  }
+
+  /**
    * Create a [[CreateDatabase]] command.
    *
    * For example:
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/command/commands.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/command/commands.scala
index 4eb8d7ff0d..a4be3bc333 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/command/commands.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/command/commands.scala
@@ -21,7 +21,7 @@ import java.util.NoSuchElementException
 
 import org.apache.spark.internal.Logging
 import org.apache.spark.rdd.RDD
-import org.apache.spark.sql.{Dataset, Row, SQLContext}
+import org.apache.spark.sql.{AnalysisException, Dataset, Row, SQLContext}
 import org.apache.spark.sql.catalyst.{CatalystTypeConverters, InternalRow, TableIdentifier}
 import org.apache.spark.sql.catalyst.errors.TreeNodeException
 import org.apache.spark.sql.catalyst.expressions.{Attribute, AttributeReference}
@@ -381,6 +381,48 @@ case class ShowDatabasesCommand(databasePattern: Option[String]) extends Runnabl
 }
 
 /**
+ * A command for users to list the properties for a table If propertyKey is specified, the value
+ * for the propertyKey is returned. If propertyKey is not specified, all the keys and their
+ * corresponding values are returned.
+ * The syntax of using this command in SQL is:
+ * {{{
+ *   SHOW TBLPROPERTIES table_name[('propertyKey')];
+ * }}}
+ */
+case class ShowTablePropertiesCommand(
+    table: TableIdentifier,
+    propertyKey: Option[String]) extends RunnableCommand {
+
+  override val output: Seq[Attribute] = {
+    val schema = AttributeReference("value", StringType, nullable = false)() :: Nil
+    propertyKey match {
+      case None => AttributeReference("key", StringType, nullable = false)() :: schema
+      case _ => schema
+    }
+  }
+
+  override def run(sqlContext: SQLContext): Seq[Row] = {
+    val catalog = sqlContext.sessionState.catalog
+
+    if (catalog.isTemporaryTable(table)) {
+      Seq.empty[Row]
+    } else {
+      val catalogTable = sqlContext.sessionState.catalog.getTable(table)
+
+      propertyKey match {
+        case Some(p) =>
+          val propValue = catalogTable
+            .properties
+            .getOrElse(p, s"Table ${catalogTable.qualifiedName} does not have property: $p")
+          Seq(Row(propValue))
+        case None =>
+          catalogTable.properties.map(p => Row(p._1, p._2)).toSeq
+      }
+    }
+  }
+}
+
+/**
  * A command for users to list all of the registered functions.
  * The syntax of using this command in SQL is:
  * {{{
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 458f36e832..8b2a5979e2 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
@@ -773,4 +773,12 @@ class DDLCommandSuite extends PlanTest {
     comparePlans(parsed2, expected2)
   }
 
+  test("show tblproperties") {
+    val parsed1 = parser.parsePlan("SHOW TBLPROPERTIES tab1")
+    val expected1 = ShowTablePropertiesCommand(TableIdentifier("tab1", None), None)
+    val parsed2 = parser.parsePlan("SHOW TBLPROPERTIES tab1('propKey1')")
+    val expected2 = ShowTablePropertiesCommand(TableIdentifier("tab1", None), Some("propKey1"))
+    comparePlans(parsed1, expected1)
+    comparePlans(parsed2, expected2)
+  }
 }