GitHub user dongjoon-hyun opened a pull request:
https://github.com/apache/spark/pull/15168
[SPARK-17612][SQL] Support `DESCRIBE table PARTITION` SQL syntax
## What changes were proposed in this pull request?
This PR implements `DESCRIBE table PARTITION` SQL Syntax again. It was
supported until Spark 1.6.2, but was dropped since 2.0.0.
**Spark 1.6.2**
```
scala> sql("CREATE TABLE partitioned_table (a STRING, b INT) PARTITIONED BY
(c STRING, d STRING)")
res1: org.apache.spark.sql.DataFrame = [result: string]
scala> sql("ALTER TABLE partitioned_table ADD PARTITION (c='Us', d=1)")
res2: org.apache.spark.sql.DataFrame = [result: string]
scala> sql("DESC partitioned_table PARTITION (c='Us', d=1)").show(false)
+----------------------------------------------------------------+
|result |
+----------------------------------------------------------------+
|a string |
|b int |
|c string |
|d string |
|
|
|# Partition Information
|
|# col_name data_type comment |
|
|
|c string |
|d string |
+----------------------------------------------------------------+
```
**Spark 2.0**
- **Before**
```
scala> sql("CREATE TABLE partitioned_table (a STRING, b INT) PARTITIONED BY
(c STRING, d STRING)")
res0: org.apache.spark.sql.DataFrame = []
scala> sql("ALTER TABLE partitioned_table ADD PARTITION (c='Us', d=1)")
res1: org.apache.spark.sql.DataFrame = []
scala> sql("DESC partitioned_table PARTITION (c='Us', d=1)").show(false)
org.apache.spark.sql.catalyst.parser.ParseException:
Unsupported SQL statement
== SQL ==
DESC partitioned_table PARTITION (c='Us', d=1)
at
org.apache.spark.sql.catalyst.parser.AbstractSqlParser$$anonfun$parsePlan$1.apply(ParseDriver.scala:58)
at
org.apache.spark.sql.catalyst.parser.AbstractSqlParser$$anonfun$parsePlan$1.apply(ParseDriver.scala:53)
at
org.apache.spark.sql.catalyst.parser.AbstractSqlParser.parse(ParseDriver.scala:82)
at
org.apache.spark.sql.execution.SparkSqlParser.parse(SparkSqlParser.scala:45)
at
org.apache.spark.sql.catalyst.parser.AbstractSqlParser.parsePlan(ParseDriver.scala:53)
at org.apache.spark.sql.SparkSession.sql(SparkSession.scala:573)
... 48 elided
```
- **After**
```
scala> sql("CREATE TABLE partitioned_table (a STRING, b INT) PARTITIONED BY
(c STRING, d STRING)")
res0: org.apache.spark.sql.DataFrame = []
scala> sql("ALTER TABLE partitioned_table ADD PARTITION (c='Us', d=1)")
res1: org.apache.spark.sql.DataFrame = []
scala> sql("DESC partitioned_table PARTITION (c='Us', d=1)").show(false)
+-----------------------+---------+-------+
|col_name |data_type|comment|
+-----------------------+---------+-------+
|a |string |null |
|b |int |null |
|c |string |null |
|d |string |null |
|# Partition Information| | |
|# col_name |data_type|comment|
|c |string |null |
|d |string |null |
+-----------------------+---------+-------+
```
## How was this patch tested?
Pass the Jenkins tests with a new testcase.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/dongjoon-hyun/spark SPARK-17612
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/15168.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #15168
----
commit 1396eb10db67382fbb99d0f28e39722ef6758d3b
Author: Dongjoon Hyun <dongj...@apache.org>
Date: 2016-09-20T19:57:47Z
[SPARK-17612][SQL] Support `DESCRIBE table PARTITION` SQL syntax
----
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