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[SPARK-28788][DOC][SQL] Document ANALYZE TABLE statement in SQL Reference

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### What changes were proposed in this pull request?
Document ANALYZE TABLE statement in SQL Reference

### Why are the changes needed?
To complete SQL reference

### Does this PR introduce any user-facing change?
Yes

***Before***:
There was no documentation for this.

***After***:
![image](https://user-images.githubusercontent.com/13592258/64046883-f8339480-cb21-11e9-85da-6617d5c96412.png)

![image](https://user-images.githubusercontent.com/13592258/64209526-9a6eb780-ce55-11e9-9004-53c5c5d24567.png)

![image](https://user-images.githubusercontent.com/13592258/64209542-a2c6f280-ce55-11e9-8624-e7349204ec8e.png)

### How was this patch tested?
Tested using jykyll build --serve

Closes #25524 from huaxingao/spark-28788.

Authored-by: Huaxin Gao <huaxing@us.ibm.com>
Signed-off-by: Xiao Li <gatorsmile@gmail.com>
This commit is contained in:
Huaxin Gao 2019-09-03 15:26:12 -07:00 committed by Xiao Li
parent 89800931aa
commit 56f2887dc8
2 changed files with 80 additions and 9 deletions
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76
docs/sql-ref-syntax-aux-analyze-table.md
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@ -19,4 +19,78 @@ license: |
limitations under the License.
---
**This page is under construction**
### Description
The `ANALYZE TABLE` statement collects statistics about the table to be used by the query optimizer to find a better query execution plan.
### Syntax
{% highlight sql %}
ANALYZE TABLE table_name [ PARTITION ( partition_col_name [ = partition_col_val ] [ , ... ] ) ]
COMPUTE STATISTICS [ NOSCAN | FOR COLUMNS col [ , ... ] | FOR ALL COLUMNS ]
{% endhighlight %}
### Parameters
<dl>
<dt><code><em>table_name</em></code></dt>
<dd>The name of an existing table.</dd>
</dl>
<dl>
<dt><code><em>PARTITION ( partition_col_name [ = partition_col_val ] [ , ... ] )</em></code></dt>
<dd>Specifies one or more partition column and value pairs. The partition value is optional.</dd>
</dl>
<dl>
<dt><code><em>[ NOSCAN | FOR COLUMNS col [ , ... ] | FOR ALL COLUMNS ]</em></code></dt>
<dd>
<ul>
<li> If no analyze option is specified, <code>ANALYZE TABLE</code> collects the table's number of rows and size in bytes. </li>
<li> <b>NOSCAN</b>
<br> Collect only the table's size in bytes ( which does not require scanning the entire table ). </li>
<li> <b>FOR COLUMNS col [ , ... ] <code> | </code> FOR ALL COLUMNS</b>
<br> Collect column statistics for each column specified, or alternatively for every column, as well as table statistics.
</li>
</ul>
</dd>
</dl>
### Examples
{% highlight sql %}
ANALYZE TABLE students COMPUTE STATISTICS NOSCAN;
DESC EXTENDED students;
......
Statistics 2820 bytes
......
ANALYZE TABLE students COMPUTE STATISTICS;
DESC EXTENDED students;
......
Statistics 2820 bytes, 3 rows
......
ANALYZE TABLE students PARTITION (student_id = 111111) COMPUTE STATISTICS;
DESC EXTENDED students PARTITION (student_id = 111111);
......
Partition Statistics 919 bytes, 1 rows
......
ANALYZE TABLE students COMPUTE STATISTICS FOR COLUMNS name;
DESC EXTENDED students name;
=default tbl=students
col_name name
data_type string
comment NULL
min NULL
max NULL
num_nulls 0
distinct_count 3
avg_col_len 11
max_col_len 13
histogram NULL
{% endhighlight %}

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docs/sql-ref-syntax-aux-analyze.md
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@ -1,7 +1,7 @@
---
layout: global
title: Reference
displayTitle: Reference
title: ANALYZE
displayTitle: ANALYZE
license: |
Licensed to the Apache Software Foundation (ASF) under one or more
contributor license agreements. See the NOTICE file distributed with
@ -19,7 +19,4 @@ license: |
limitations under the License.
---
Spark SQL is a Apache Spark's module for working with structured data.
This guide is a reference for Structured Query Language (SQL) for Apache
Spark. This document describes the SQL constructs supported by Spark in detail
along with usage examples when applicable.
* [ANALYZE TABLE statement](sql-ref-syntax-aux-analyze-table.html)