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spark-instrumented-optimizer/docs/sql-ref-syntax-aux-cache-uncache-table.md
Huaxin Gao e4f70023ad [SPARK-28830][DOC][SQL] Document UNCACHE TABLE statement in SQL Reference 
### What changes were proposed in this pull request?
Document UNCACHE TABLE statement in SQL Reference
### Why are the changes needed?
To complete SQL Reference

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

After change:

![image](https://user-images.githubusercontent.com/13592258/64299133-e04a7f00-cf2c-11e9-8f39-9b288e46c995.png)

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

Closes #25540 from huaxingao/spark-28830.

Lead-authored-by: Huaxin Gao <huaxing@us.ibm.com>
Co-authored-by: Xiao Li <gatorsmile@gmail.com>
Signed-off-by: Xiao Li <gatorsmile@gmail.com>
2019-09-04 21:42:01 -07:00

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global UNCACHE TABLE UNCACHE 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

UNCACHE TABLE removes the entries and associated data from the in-memory and/or on-disk cache for a given table. The underlying entries should already have been brought to cache by previous CACHE TABLE operation. UNCACHE TABLE on a non-existent table throws Exception if IF EXISTS is not specified.

Syntax

{% highlight sql %} UNCACHE TABLE [ IF EXISTS ] table_name {% endhighlight %}

Parameters

table_name
The name of the table to be uncached.
### Examples {% highlight sql %} UNCACHE TABLE t1; {% endhighlight %} ### Related Statements * [CACHE TABLE](sql-ref-syntax-aux-cache-cache-table.html) * [CLEAR CACHE](sql-ref-syntax-aux-cache-clear-cache.html)