GitHub user liancheng opened a pull request:
https://github.com/apache/spark/pull/13025
[SPARK-14127][SQL] "DESC <table>": Extracts schema information from table
properties for data source tables
## What changes were proposed in this pull request?
This is a follow-up of #12934 and #12844. This PR adds a set of utility
methods in `DDLUtils` to help extract schema information (user-defined schema,
partition columns, and bucketing information) from data source table
properties. These utility methods are then used in `DescribeTableCommand` to
refine output for data source tables. Before this PR, the aforementioned schema
information are only shown as table properties, which are hard to read.
Sample output:
```
+----------------------------+---------------------------------------------------------+-------+
|col_name |data_type
|comment|
+----------------------------+---------------------------------------------------------+-------+
|a |bigint
| |
|b |bigint
| |
|c |bigint
| |
|d |bigint
| |
|# Partition Information |
| |
|# col_name |
| |
|d |
| |
| |
| |
|# Detailed Table Information|
| |
|Database: |default
| |
|Owner: |lian
| |
|Create Time: |Tue May 10 03:20:34 PDT 2016
| |
|Last Access Time: |Wed Dec 31 16:00:00 PST 1969
| |
|Location:
|file:/Users/lian/local/src/spark/workspace-a/target/... | |
|Table Type: |MANAGED
| |
|Table Parameters: |
| |
| rawDataSize |-1
| |
| numFiles |1
| |
| transient_lastDdlTime |1462875634
| |
| totalSize |684
| |
| spark.sql.sources.provider|parquet
| |
| EXTERNAL |FALSE
| |
| COLUMN_STATS_ACCURATE |false
| |
| numRows |-1
| |
| |
| |
|# Storage Information |
| |
|SerDe Library:
|org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe | |
|InputFormat:
|org.apache.hadoop.mapred.SequenceFileInputFormat | |
|OutputFormat:
|org.apache.hadoop.hive.ql.io.HiveSequenceFileOutputFormat| |
|Compressed: |No
| |
|Num Buckets: |2
| |
|Bucket Columns: |[b]
| |
|Sort Columns: |[c]
| |
|Storage Desc Parameters: |
| |
| path
|file:/Users/lian/local/src/spark/workspace-a/target/... | |
| serialization.format |1
| |
+----------------------------+---------------------------------------------------------+-------+
```
## How was this patch tested?
Test cases are added in `HiveDDLSuite` to check command output.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/liancheng/spark
spark-14127-extract-schema-info
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/13025.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 #13025
----
commit 2eccb6e1dbcd47e89cbf5fcd5a79f3a65cee0672
Author: Cheng Lian <l...@databricks.com>
Date: 2016-05-10T10:36:01Z
Extracts schema information from table properties for data source tables
----
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