Github user OopsOutOfMemory commented on a diff in the pull request:
https://github.com/apache/spark/pull/4127#discussion_r23359955
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/execution/commands.scala ---
@@ -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
--- End diff --
after finish SPARK-5182. we can do it like this:
```
val logicalRelation = sqlContext.executePlan(tblRelation).analyzed
val rows = new ArrayBuffer[Row]()
rows ++= logicalRelation.schema.fields.map{field =>
Row(field.name, field.dataType.toSimpleString, null)}
val partitionFields = logicalRelation.schema.getPartitionedCols()
if (partitionFields.nonEmpty) {
val partColumnRows =
partitionFields.map(field => Row(field.getName,
field.getType.toSimpleString, null))
rows ++=
Seq(("# Partition Information", "", "")) ++
("col_name","data_type","comment") ++
partColumnRows
}
```
For `extended` we can do it later and discuss to show detail information.
```
if (isExtended) {
rows ++= Seq(("Detailed Table Information", //get some detail info
from table, ""))
}
```
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