Indhumathi27 commented on a change in pull request #4113:
URL:
https://github.com/apache/carbondata/pull/4113#discussion_r607512702##########
File path: integration/spark/src/main/scala/org/apache/spark/sql/parser/CarbonSparkSqlParserUtil.scala
##########
@@ -744,6 +747,52 @@ object CarbonSparkSqlParserUtil {
CarbonAlterTableAddColumnCommand(alterTableAddColumnsModel)
}
+
+ def describeColumn(
+ databaseNameOp: Option[String],
+ tableName: String,
+ inputFields: java.util.List[String]
+ ): CarbonDescribeColumnCommand = {
+ val sparkSession = SparkSQLUtil.getSparkSession
+ validateTableExists(databaseNameOp, tableName, sparkSession)
+ val relation = CarbonEnv
+ .getInstance(sparkSession)
+ .carbonMetaStore
+ .lookupRelation(databaseNameOp, tableName)(sparkSession)
+ .asInstanceOf[CarbonRelation]
+ val tableSchema = StructType.fromAttributes(relation.output)
+ val carbonTable = relation.carbonTable
+ val inputColumn = tableSchema.find(_.name.equalsIgnoreCase(inputFields.get(0)))
+ if (!inputColumn.isDefined) {
+ throw new MalformedCarbonCommandException(
+ s"${inputFields.get(0)} not present in schema of table: $tableName")
+ }
+ CarbonDescribeColumnCommand(
+ carbonTable,
+ inputFields,
+ inputColumn.get
+ )
+ }
+
+ def describeShort(
+ databaseNameOp: Option[String],
+ tableName: String
+ ): CarbonDescribeShortCommand = {
+ val sparkSession = SparkSQLUtil.getSparkSession
+ validateTableExists(databaseNameOp, tableName, sparkSession)
Review comment:
Can move duplicate code from describeShort and describeColumn to common method
##########
File path: integration/spark/src/main/scala/org/apache/spark/sql/parser/CarbonExtensionSpark2SqlParser.scala
##########
@@ -27,7 +28,26 @@ import org.apache.spark.sql.catalyst.plans.logical._
class CarbonExtensionSpark2SqlParser extends CarbonSpark2SqlParser {
override protected lazy val extendedSparkSyntax: Parser[LogicalPlan] =
- loadDataNew | alterTableAddColumns | explainPlan
+ loadDataNew | alterTableAddColumns | explainPlan | describeColumn | describeShort
Review comment:
I think, no need to define here, since CarbonExtensionSpark2SqlParser extends CarbonSpark2SqlParser.
##########
File path: integration/spark/src/main/scala/org/apache/spark/sql/execution/command/table/CarbonDescribeFormattedCommand.scala
##########
@@ -370,3 +373,134 @@ private[sql] case class CarbonDescribeFormattedCommand(
override protected def opName: String = "DESC FORMATTED"
}
+
+case class CarbonDescribeColumnCommand(
+ carbonTable: CarbonTable,
+ inputFieldNames: java.util.List[String],
+ field: StructField)
+ extends MetadataCommand {
+
+ override val output: Seq[Attribute] = Seq(
+ // Column names are based on Hive.
+ AttributeReference("col_name", StringType, nullable = false,
+ new MetadataBuilder().putString("comment", "name of the column").build())(),
+ AttributeReference("data_type", StringType, nullable = false,
+ new MetadataBuilder().putString("comment", "data type of the column").build())(),
+ AttributeReference("comment", StringType, nullable = true,
+ new MetadataBuilder().putString("comment", "comment of the column").build())()
+ )
+
+ override def processMetadata(sparkSession: SparkSession): Seq[Row] = {
+ setAuditTable(carbonTable)
+ var results = Seq[(String, String, String)]()
+ var currField = field
+ val inputFieldsIterator = inputFieldNames.iterator()
+ var inputColumn = inputFieldsIterator.next()
+ while (results.size == 0) {
+ breakable {
+ if (currField.dataType.typeName.equalsIgnoreCase(CarbonCommonConstants.ARRAY)) {
+ if (inputFieldsIterator.hasNext) {
+ val nextField = inputFieldsIterator.next()
+ if (!nextField.equalsIgnoreCase("item")) {
+ throw handleException(nextField, currField.name, carbonTable.getTableName)
+ }
+ currField = StructField("item", currField.dataType.asInstanceOf[ArrayType].elementType)
+ inputColumn += "." + currField.name
+ break()
+ }
+ val colComment = currField.getComment().getOrElse("null")
+ results = Seq((inputColumn,
+ currField.dataType.typeName, currField.getComment().getOrElse("null")),
+ ("## Children of " + inputColumn + ": ", "", ""))
+ results ++= Seq(("item", currField.dataType.asInstanceOf[ArrayType]
+ .elementType.simpleString, colComment))
Review comment:
colComment given for Parent Column, will be displayed while describe child columns also?
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