spark-instrumented-optimizer/docs/sql-ref-syntax-ddl-repair-table.md
Takeshi Yamamuro 179289f0bf [SPARK-31383][SQL][DOC] Clean up the SQL documents in docs/sql-ref*
### What changes were proposed in this pull request?

This PR intends to clean up the SQL documents in `doc/sql-ref*`.
Main changes are as follows;

 - Fixes wrong syntaxes and capitalize sub-titles
 - Adds some DDL queries in `Examples` so that users can run examples there
 - Makes query output in `Examples` follows the `Dataset.showString` (right-aligned) format
 - Adds/Removes spaces, Indents, or blank lines to follow the format below;

```
---
license...
---

### Description

Writes what's the syntax is.

### Syntax

{% highlight sql %}
SELECT...
    WHERE... // 4 indents after the second line
    ...
{% endhighlight %}

### Parameters

<dl>

  <dt><code><em>Param Name</em></code></dt>
  <dd>
    Param Description
  </dd>
  ...
</dl>

### Examples

{% highlight sql %}
-- It is better that users are able to execute example queries here.
-- So, we prepare test data in the first section if possible.
CREATE TABLE t (key STRING, value DOUBLE);
INSERT INTO t VALUES
    ('a', 1.0), ('a', 2.0), ('b', 3.0), ('c', 4.0);

-- query output has 2 indents and it follows the `Dataset.showString`
-- format (right-aligned).
SELECT * FROM t;
  +---+-----+
  |key|value|
  +---+-----+
  |  a|  1.0|
  |  a|  2.0|
  |  b|  3.0|
  |  c|  4.0|
  +---+-----+

-- Query statements after the second line have 4 indents.
SELECT key, SUM(value)
    FROM t
    GROUP BY key;
  +---+----------+
  |key|sum(value)|
  +---+----------+
  |  c|       4.0|
  |  b|       3.0|
  |  a|       3.0|
  +---+----------+
...
{% endhighlight %}

### Related Statements

 * [XXX](xxx.html)
 * ...
```

### Why are the changes needed?

The most changes of this PR are pretty minor, but I think the consistent formats/rules to write documents are important for long-term maintenance in our community

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

Yes.

### How was this patch tested?

Manually checked.

Closes #28151 from maropu/MakeRightAligned.

Authored-by: Takeshi Yamamuro <yamamuro@apache.org>
Signed-off-by: Sean Owen <srowen@gmail.com>
2020-04-12 23:40:36 -05:00

2.5 KiB

layout title displayTitle license
global REPAIR TABLE REPAIR TABLE Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

Description

MSCK REPAIR TABLE recovers all the partitions in the directory of a table and updates the Hive metastore. When creating a table using PARTITIONED BY clause, partitions are generated and registered in the Hive metastore. However, if the partitioned table is created from existing data, partitions are not registered automatically in the Hive metastore. User needs to run MSCK REPAIR TABLE to register the partitions. MSCK REPAIR TABLE on a non-existent table or a table without partitions throws an exception. Another way to recover partitions is to use ALTER TABLE RECOVER PARTITIONS.

Syntax

{% highlight sql %} MSCK REPAIR TABLE table_identifier {% endhighlight %}

Parameters

table_identifier
Specifies the name of the table to be repaired. The table name may be optionally qualified with a database name.

Syntax: [ database_name. ] table_name

Examples

{% highlight sql %} -- create a partitioned table from existing data /tmp/namesAndAges.parquet CREATE TABLE t1 (name STRING, age INT) USING parquet PARTITIONED BY (age) LOCATION "/tmp/namesAndAges.parquet";

-- SELECT * FROM t1 does not return results SELECT * FROM t1;

-- run MSCK REPAIR TABLE to recovers all the partitions MSCK REPAIR TABLE t1;

-- SELECT * FROM t1 returns results SELECT * FROM t1; +-------+---+ | name|age| +-------+---+ |Michael| 20| +-------+---+ | Justin| 19| +-------+---+ | Andy| 30| +-------+---+ {% endhighlight %}