[SPARK-5135][SQL] Add support for describe [extended] table to DDL in SQLContext

sql/catalyst/src/main/scala/org/apache/spark/sql/types/dataTypes.scala

@@ -227,8 +227,9 @@ abstract class DataType {
   def json: String = compact(render(jsonValue))
 
   def prettyJson: String = pretty(render(jsonValue))
-}
 
+  def toSimpleString: String = typeName
+}
 
 /**
  * :: DeveloperApi ::
@@ -240,9 +241,9 @@ abstract class DataType {
 @DeveloperApi
 case object NullType extends DataType {
   override def defaultSize: Int = 1
+  override def toSimpleString = "null"
 }
 
-
 protected[sql] object NativeType {
   val all = Seq(
     IntegerType, BooleanType, LongType, DoubleType, FloatType, ShortType, ByteType, StringType)
@@ -300,6 +301,8 @@ case object StringType extends NativeType with PrimitiveType {
    * The default size of a value of the StringType is 4096 bytes.
    */
   override def defaultSize: Int = 4096
+
+  override def toSimpleString = "string"
 }
 
 
@@ -329,6 +332,8 @@ case object BinaryType extends NativeType with PrimitiveType {
    * The default size of a value of the BinaryType is 4096 bytes.
    */
   override def defaultSize: Int = 4096
+
+  override def toSimpleString = "binary"
 }
 
 
@@ -349,6 +354,8 @@ case object BooleanType extends NativeType with PrimitiveType {
    * The default size of a value of the BooleanType is 1 byte.
    */
   override def defaultSize: Int = 1
+
+  override def toSimpleString = "boolean"
 }
 
 
@@ -374,6 +381,8 @@ case object TimestampType extends NativeType {
    * The default size of a value of the TimestampType is 8 bytes.
    */
   override def defaultSize: Int = 8
+
+  override def toSimpleString = "timestamp"
 }
 
 
@@ -399,6 +408,8 @@ case object DateType extends NativeType {
    * The default size of a value of the DateType is 8 bytes.
    */
   override def defaultSize: Int = 8
+
+  override def toSimpleString = "date"
 }
 
 
@@ -450,6 +461,8 @@ case object LongType extends IntegralType {
    * The default size of a value of the LongType is 8 bytes.
    */
   override def defaultSize: Int = 8
+
+  override def toSimpleString = "bigint"
 }
 
 
@@ -472,6 +485,8 @@ case object IntegerType extends IntegralType {
    * The default size of a value of the IntegerType is 4 bytes.
    */
   override def defaultSize: Int = 4
+
+  override def toSimpleString = "int"
 }
 
 
@@ -494,6 +509,8 @@ case object ShortType extends IntegralType {
    * The default size of a value of the ShortType is 2 bytes.
    */
   override def defaultSize: Int = 2
+
+  override def toSimpleString = "smallint"
 }
 
 
@@ -516,6 +533,8 @@ case object ByteType extends IntegralType {
    * The default size of a value of the ByteType is 1 byte.
    */
   override def defaultSize: Int = 1
+
+  override def toSimpleString = "tinyint"
 }
 
 
@@ -575,6 +594,11 @@ case class DecimalType(precisionInfo: Option[PrecisionInfo]) extends FractionalT
    * The default size of a value of the DecimalType is 4096 bytes.
    */
   override def defaultSize: Int = 4096
+
+  override def toSimpleString = precisionInfo match {
+    case Some(PrecisionInfo(precision, scale)) => s"decimal($precision,$scale)"
+    case None => "decimal(10,0)"
+  }
 }
 
 
@@ -630,6 +654,8 @@ case object DoubleType extends FractionalType {
    * The default size of a value of the DoubleType is 8 bytes.
    */
   override def defaultSize: Int = 8
+
+  override def toSimpleString = "double"
 }
 
 
@@ -653,6 +679,8 @@ case object FloatType extends FractionalType {
    * The default size of a value of the FloatType is 4 bytes.
    */
   override def defaultSize: Int = 4
+
+  override def toSimpleString = "float"
 }
 
 
@@ -697,6 +725,8 @@ case class ArrayType(elementType: DataType, containsNull: Boolean) extends DataT
    * (We assume that there are 100 elements).
    */
   override def defaultSize: Int = 100 * elementType.defaultSize
+
+  override def toSimpleString = s"array<${elementType.toSimpleString}>"
 }
 
 
@@ -871,6 +901,11 @@ case class StructType(fields: Array[StructField]) extends DataType with Seq[Stru
    * The default size of a value of the StructType is the total default sizes of all field types.
    */
   override def defaultSize: Int = fields.map(_.dataType.defaultSize).sum
+
+  override def toSimpleString = {
+    val fieldTypes = fields.map(field => s"${field.name}:${field.dataType.toSimpleString}")
+    s"struct<${fieldTypes.mkString(",")}>"
+  }
 }
 
 
@@ -921,6 +956,8 @@ case class MapType(
    * (We assume that there are 100 elements).
    */
   override def defaultSize: Int = 100 * (keyType.defaultSize + valueType.defaultSize)
+
+  override def toSimpleString = s"map<${keyType.toSimpleString},${valueType.toSimpleString}>"
 }
 
 

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

@@ -21,10 +21,12 @@ import org.apache.spark.Logging
 import org.apache.spark.annotation.DeveloperApi
 import org.apache.spark.rdd.RDD
 import org.apache.spark.sql.{SchemaRDD, SQLConf, SQLContext}
+import org.apache.spark.sql.catalyst.analysis.UnresolvedRelation
 import org.apache.spark.sql.catalyst.errors.TreeNodeException
 import org.apache.spark.sql.catalyst.expressions.{Row, Attribute}
 import org.apache.spark.sql.catalyst.plans.logical
 import org.apache.spark.sql.catalyst.plans.logical.LogicalPlan
+import scala.collection.mutable.ArrayBuffer
 
 /**
  * A logical command that is executed for its side-effects.  `RunnableCommand`s are
@@ -178,3 +180,34 @@ case class DescribeCommand(
     child.output.map(field => Row(field.name, field.dataType.toString, null))
   }
 }
+
+/**
+ * :: DeveloperApi ::
+ */
+@DeveloperApi
+case class DDLDescribeCommand(
+    dbName: Option[String],
+    tableName: String, isExtended: Boolean) extends RunnableCommand {
+
+  override def run(sqlContext: SQLContext) = {
+    val tblRelation = dbName match {
+      case Some(db) => UnresolvedRelation(Seq(db, tableName))
+      case None => UnresolvedRelation(Seq(tableName))
+    }
+    val logicalRelation = sqlContext.executePlan(tblRelation).analyzed
+    val rows = new ArrayBuffer[Row]()
+    rows ++= logicalRelation.schema.fields.map{field =>
+      Row(field.name, field.dataType.toSimpleString, null)}
+
+    /*
+     * TODO if future support partition table, add header below:
+     * # Partition Information
+     * # col_name data_type comment
+     */
+    if (isExtended) { // TODO describe extended table
+      // rows += Row("# extended", null, null)
+    }
+    rows
+   }
+}
+

sql/core/src/main/scala/org/apache/spark/sql/sources/ddl.scala

@@ -25,9 +25,10 @@ import org.apache.spark.Logging
 import org.apache.spark.sql.{SchemaRDD, SQLContext}
 import org.apache.spark.sql.catalyst.plans.logical._
 import org.apache.spark.sql.catalyst.SqlLexical
-import org.apache.spark.sql.execution.RunnableCommand
+import org.apache.spark.sql.execution.{DDLDescribeCommand, RunnableCommand}
 import org.apache.spark.sql.types._
 import org.apache.spark.util.Utils
+import org.apache.spark.sql.catalyst.analysis.UnresolvedRelation
 
 /**
  * A parser for foreign DDL commands.
@@ -61,6 +62,8 @@ private[sql] class DDLParser extends StandardTokenParsers with PackratParsers wi
   protected val TABLE = Keyword("TABLE")
   protected val USING = Keyword("USING")
   protected val OPTIONS = Keyword("OPTIONS")
+  protected val DESCRIBE = Keyword("DESCRIBE")
+  protected val EXTENDED = Keyword("EXTENDED")
 
   // Data types.
   protected val STRING = Keyword("STRING")
@@ -89,7 +92,7 @@ private[sql] class DDLParser extends StandardTokenParsers with PackratParsers wi
 
   override val lexical = new SqlLexical(reservedWords)
 
-  protected lazy val ddl: Parser[LogicalPlan] = createTable
+  protected lazy val ddl: Parser[LogicalPlan] = createTable | describeTable
 
   /**
    * `CREATE [TEMPORARY] TABLE avroTable
@@ -112,6 +115,16 @@ private[sql] class DDLParser extends StandardTokenParsers with PackratParsers wi
 
   protected lazy val tableCols: Parser[Seq[StructField]] =  "(" ~> repsep(column, ",") <~ ")"
 
+  /*
+   * describe [extended] table avroTable
+   * This will display all columns of table `avroTable` includes column_name,column_type,nullable
+   */
+  protected lazy val describeTable: Parser[LogicalPlan] =
+    (DESCRIBE ~> opt(EXTENDED)) ~ (ident <~ ".").? ~ ident  ^^ {
+      case e ~ db ~ tbl  =>
+        DDLDescribeCommand(db, tbl, e.nonEmpty)
+   }
+
   protected lazy val options: Parser[Map[String, String]] =
     "(" ~> repsep(pair, ",") <~ ")" ^^ { case s: Seq[(String, String)] => s.toMap }
 

sql/core/src/test/scala/org/apache/spark/sql/sources/DDLTestSuite.scala

@@ -0,0 +1,121 @@
+/*
+* Licensed to the Apache Software Foundation (ASF) under one or more
+* contributor license agreements.  See the NOTICE file distributed with
+* this work for additional information regarding copyright ownership.
+* The ASF licenses this file to You under the Apache License, Version 2.0
+* (the "License"); you may not use this file except in compliance with
+* the License.  You may obtain a copy of the License at
+*
+*    http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+package org.apache.spark.sql.sources
+
+import org.apache.spark.sql._
+import org.apache.spark.sql.types._
+
+class DDLScanSource extends RelationProvider {
+  override def createRelation(
+      sqlContext: SQLContext,
+      parameters: Map[String, String]): BaseRelation = {
+    SimpleDDLScan(parameters("from").toInt, parameters("TO").toInt)(sqlContext)
+  }
+}
+
+case class SimpleDDLScan(from: Int, to: Int)(@transient val sqlContext: SQLContext)
+  extends TableScan {
+
+  override def schema =
+    StructType(Seq(
+      StructField("intType", IntegerType, nullable = false),
+      StructField("stringType", StringType, nullable = false),
+      StructField("dateType", DateType, nullable = false),
+      StructField("timestampType", TimestampType, nullable = false),
+      StructField("doubleType", DoubleType, nullable = false),
+      StructField("bigintType", LongType, nullable = false),
+      StructField("tinyintType", ByteType, nullable = false),
+      StructField("decimalType", DecimalType.Unlimited, nullable = false),
+      StructField("fixedDecimalType", DecimalType(5,1), nullable = false),
+      StructField("binaryType", BinaryType, nullable = false),
+      StructField("booleanType", BooleanType, nullable = false),
+      StructField("smallIntType", ShortType, nullable = false),
+      StructField("floatType", FloatType, nullable = false),
+      StructField("mapType", MapType(StringType, StringType)),
+      StructField("arrayType", ArrayType(StringType)),
+      StructField("structType",
+        StructType(StructField("f1",StringType) ::
+          StructField("f2",IntegerType) :: Nil
+        )
+      )
+    ))
+
+
+  override def buildScan() = sqlContext.sparkContext.parallelize(from to to).map { e =>
+    Row(s"people$e", e * 2)
+  }
+}
+
+class DDLTestSuite extends DataSourceTest {
+  import caseInsensisitiveContext._
+
+  before {
+    sql(
+      """
+      |CREATE TEMPORARY TABLE ddlPeople
+      |USING org.apache.spark.sql.sources.DDLScanSource
+      |OPTIONS (
+      |  From '1',
+      |  To '10'
+      |)
+      """.stripMargin)
+  }
+
+  sqlTest(
+    "describe ddlPeople",
+    Seq(
+      Row("intType", "int", null),
+      Row("stringType", "string", null),
+      Row("dateType", "date", null),
+      Row("timestampType", "timestamp", null),
+      Row("doubleType", "double", null),
+      Row("bigintType", "bigint", null),
+      Row("tinyintType", "tinyint", null),
+      Row("decimalType", "decimal(10,0)", null),
+      Row("fixedDecimalType", "decimal(5,1)", null),
+      Row("binaryType", "binary", null),
+      Row("booleanType", "boolean", null),
+      Row("smallIntType", "smallint", null),
+      Row("floatType", "float", null),
+      Row("mapType", "map<string,string>", null),
+      Row("arrayType", "array<string>", null),
+      Row("structType", "struct<f1:string,f2:int>", null)
+    ))
+
+  sqlTest(
+    "describe extended ddlPeople",
+    Seq(
+      Row("intType", "int", null),
+      Row("stringType", "string", null),
+      Row("dateType", "date", null),
+      Row("timestampType", "timestamp", null),
+      Row("doubleType", "double", null),
+      Row("bigintType", "bigint", null),
+      Row("tinyintType", "tinyint", null),
+      Row("decimalType", "decimal(10,0)", null),
+      Row("fixedDecimalType", "decimal(5,1)", null),
+      Row("binaryType", "binary", null),
+      Row("booleanType", "boolean", null),
+      Row("smallIntType", "smallint", null),
+      Row("floatType", "float", null),
+      Row("mapType", "map<string,string>", null),
+      Row("arrayType", "array<string>", null),
+      Row("structType", "struct<f1:string,f2:int>", null)
+      // Row("# extended", null, null)
+    ))
+}