Herman's comment

Author: dilipbiswal

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/catalog/SessionCatalog.scala

@@ -163,6 +163,7 @@ class SessionCatalog(
   /**
    * Retrieve the metadata of an existing metastore table.
    * If no database is specified, assume the table is in the current database.
+   * If the specified table is not found in the database then an [[AnalysisException]] is thrown.
    */
   def getTable(name: TableIdentifier): CatalogTable = {
     val db = name.database.getOrElse(currentDb)

sql/core/src/main/scala/org/apache/spark/sql/execution/SparkSqlParser.scala

@@ -93,10 +93,9 @@ 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.
+   * 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')];
@@ -236,14 +235,17 @@ 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 = 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)

sql/core/src/main/scala/org/apache/spark/sql/execution/command/commands.scala

@@ -374,10 +374,9 @@ 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.
+ * 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')];
@@ -395,26 +394,29 @@ case class ShowTablePropertiesCommand(
       AttributeReference("key", StringType, nullable = false)() ::
         AttributeReference("value", StringType, nullable = false)() :: Nil
     }
-    propertyKey.map(p => withKeySchema).getOrElse(noKeySchema)
+    propertyKey match {
+      case None => noKeySchema
+      case _ => withKeySchema
+    }
   }
 
   override def run(sqlContext: SQLContext): Seq[Row] = {
     val catalog = sqlContext.sessionState.catalog
 
     if (catalog.isTemporaryTable(table)) {
-      throw new AnalysisException("This operation is unsupported for temporary tables")
-    }
-    val catalogTable = sqlContext.sessionState.catalog.getTable(table)
-
-    propertyKey match {
-      case Some(p) =>
-        val errorStr = s"Table ${catalogTable.qualifiedName} does not have property: $p"
-        val propValue = catalogTable
-          .properties
-          .getOrElse(p, throw new AnalysisException(errorStr))
-        Seq(Row(propValue))
-      case None =>
-        catalogTable.properties.map(p => Row(p._1, p._2)).toSeq
+      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
+      }
     }
   }
 }

sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/HiveCommandSuite.scala

@@ -98,30 +98,28 @@ class HiveCommandSuite extends QueryTest with SQLTestUtils with TestHiveSingleto
     }.getMessage
     assert(message1.contains("Table badtable not found in database default"))
 
-    val message2 = intercept[AnalysisException] {
-      sql("SHOW TBLPROPERTIES parquet_tab1('invalid.prop.key')")
-    }.getMessage
-    assert(
-      message2.contains(s"Table default.parquet_tab1 does not have property: invalid.prop.key"))
+    // When key is not found, a row containing the error is returned.
+    checkAnswer(
+      sql("SHOW TBLPROPERTIES parquet_tab1('invalid.prop.key')"),
+      Row("Table default.parquet_tab1 does not have property: invalid.prop.key") :: Nil
+    )
   }
 
   test("show tblproperties for hive table") {
     checkAnswer(sql("SHOW TBLPROPERTIES parquet_tab2('prop1Key')"), Row("prop1Val"))
     checkAnswer(sql("SHOW TBLPROPERTIES parquet_tab2('`prop2Key`')"), Row("prop2Val"))
   }
 
-  test("show tblproperties for spark temporary table - error") {
+  test("show tblproperties for spark temporary table - empty row") {
     withTempTable("parquet_temp") {
       sql(
         """
           |CREATE TEMPORARY TABLE parquet_temp (c1 INT, c2 STRING)
           |USING org.apache.spark.sql.parquet.DefaultSource
         """.stripMargin)
 
-      val message1 = intercept[AnalysisException] {
-        sql("SHOW TBLPROPERTIES parquet_temp")
-      }.getMessage
-      assert(message1.contains("This operation is unsupported for temporary tables"))
+      // An empty sequence of row is returned for session temporary table.
+      checkAnswer(sql("SHOW TBLPROPERTIES parquet_temp"), Nil)
     }
   }
 }