Github user OopsOutOfMemory commented on a diff in the pull request:
https://github.com/apache/spark/pull/4127#discussion_r23276556
--- 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 --
Here what I mean is to display the normal columns information first and
then `append` the partitioned columns at bottom of the normal columns
description. Like below:
```
CREATE TABLE temp_shengli (
viewTime int,
userid bigint,
page_url string,
referrer_url string,
ip string comment 'IP Address of the User'
)
comment 'This is the page view table'
PARTITIONED BY(date string, pos string)
````
To describe it:
```
viewtime int None
userid bigint None
page_url string None
referrer_url string None
ip string IP Address of the User
date string None
pos string None
# Partition Information
# col_name data_type comment
date string None
pos string None
```
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