184074de22
### What changes were proposed in this pull request? In Hive mode, permanent functions are shared with Hive metastore so that functions may be modified by other Hive client. With in long-lived spark scene, it's hard to update the change of function. Here are 2 reasons: * Spark cache the function in memory using `FunctionRegistry`. * User may not know the location or classname of udf when using `replace function`. Note that we use v2 command code path to add new command. ### Why are the changes needed? Give a easy way to make spark function registry sync with Hive metastore. Then we can call ``` refresh function functionName ``` ### Does this PR introduce _any_ user-facing change? Yes, new command. ### How was this patch tested? New UT. Closes #28840 from ulysses-you/SPARK-31999. Authored-by: ulysses <youxiduo@weidian.com> Signed-off-by: Wenchen Fan <wenchen@databricks.com>
53 lines
1.8 KiB
Markdown
53 lines
1.8 KiB
Markdown
---
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layout: global
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title: UNCACHE TABLE
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displayTitle: UNCACHE TABLE
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license: |
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Licensed to the Apache Software Foundation (ASF) under one or more
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contributor license agreements. See the NOTICE file distributed with
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this work for additional information regarding copyright ownership.
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The ASF licenses this file to You under the Apache License, Version 2.0
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(the "License"); you may not use this file except in compliance with
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the License. You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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---
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### Description
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`UNCACHE TABLE` removes the entries and associated data from the in-memory and/or on-disk cache for a given table or view. The
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underlying entries should already have been brought to cache by previous `CACHE TABLE` operation. `UNCACHE TABLE` on a non-existent table throws an exception if `IF EXISTS` is not specified.
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### Syntax
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```sql
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UNCACHE TABLE [ IF EXISTS ] table_identifier
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```
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### Parameters
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* **table_identifier**
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Specifies the table or view name to be uncached. The table or view name may be optionally qualified with a database name.
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**Syntax:** `[ database_name. ] table_name`
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### Examples
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```sql
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UNCACHE TABLE t1;
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```
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### Related Statements
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* [CACHE TABLE](sql-ref-syntax-aux-cache-cache-table.html)
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* [CLEAR CACHE](sql-ref-syntax-aux-cache-clear-cache.html)
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* [REFRESH TABLE](sql-ref-syntax-aux-cache-refresh-table.html)
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* [REFRESH](sql-ref-syntax-aux-cache-refresh.html)
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* [REFRESH FUNCTION](sql-ref-syntax-aux-cache-refresh-function.html) |