d3596c04b0
### What changes were proposed in this pull request? This PR extends the RESET command to support reset SQL configuration one by one. ### Why are the changes needed? Currently, the reset command only supports restore all of the runtime configurations to their defaults. In most cases, users do not want this, but just want to restore one or a small group of settings. The SET command can work as a workaround for this, but you have to keep the defaults in your mind or by temp variables, which turns out not very convenient to use. Hive supports this: https://cwiki.apache.org/confluence/display/Hive/HiveServer2+Clients#HiveServer2Clients-BeelineExample reset <key> | Resets the value of a particular configuration variable (key) to the default value.Note: If you misspell the variable name, Beeline will not show an error. -- | -- PostgreSQL supports this too https://www.postgresql.org/docs/9.1/sql-reset.html ### Does this PR introduce _any_ user-facing change? yes, reset can restore one configuration now ### How was this patch tested? add new unit tests. Closes #29202 from yaooqinn/SPARK-32406. Authored-by: Kent Yao <yaooqinn@hotmail.com> Signed-off-by: Dongjoon Hyun <dongjoon@apache.org>
57 lines
2 KiB
Markdown
57 lines
2 KiB
Markdown
---
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layout: global
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title: RESET
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displayTitle: RESET
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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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The RESET command resets runtime configurations specific to the current session which were set via the [SET](sql-ref-syntax-aux-conf-mgmt-set.html) command to their default values.
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### Syntax
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```sql
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RESET;
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RESET configuration_key;
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```
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### Parameters
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* **(none)**
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Reset any runtime configurations specific to the current session which were set via the [SET](sql-ref-syntax-aux-conf-mgmt-set.html) command to their default values.
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* **configuration_key**
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Restore the value of the `configuration_key` to the default value. If the default value is undefined, the `configuration_key` will be removed.
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### Examples
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```sql
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-- Reset any runtime configurations specific to the current session which were set via the SET command to their default values.
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RESET;
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-- If you start your application with --conf spark.foo=bar and set spark.foo=foobar in runtime, the example below will restore it to 'bar'. If spark.foo is not specified during starting, the example bellow will remove this config from the SQLConf. It will ignore nonexistent keys.
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RESET spark.abc;
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```
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### Related Statements
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* [SET](sql-ref-syntax-aux-conf-mgmt-set.html)
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