Revision be7f1e9979c38b1358b0af2b358bacb0bd523c80 authored by Dongjoon Hyun on 24 January 2024, 00:38:45 UTC, committed by Dongjoon Hyun on 24 January 2024, 00:38:53 UTC
### What changes were proposed in this pull request?

This PR aims to fix `spark-daemon.sh` usage by adding `decommission` command.

### Why are the changes needed?

This was missed when SPARK-20628 added `decommission` command at Apache Spark 3.1.0. The command has been used like the following.

https://github.com/apache/spark/blob/0356ac00947282b1a0885ad7eaae1e25e43671fe/sbin/decommission-worker.sh#L41

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

No, this is only a change on usage message.

### How was this patch tested?

Manual review.

### Was this patch authored or co-authored using generative AI tooling?

No.

Closes #44856 from dongjoon-hyun/SPARK-46817.

Authored-by: Dongjoon Hyun <dhyun@apple.com>
Signed-off-by: Dongjoon Hyun <dhyun@apple.com>
(cherry picked from commit 00a92d328576c39b04cfd0fdd8a30c5a9bc37e36)
Signed-off-by: Dongjoon Hyun <dhyun@apple.com>
1 parent 05f7aa5
Raw File
sql-ref-syntax-ddl-create-view.md
---
layout: global
title: CREATE VIEW
displayTitle: CREATE VIEW 
license: |
  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

Views are based on the result-set of an `SQL` query. `CREATE VIEW` constructs
a virtual table that has no physical data therefore other operations like
`ALTER VIEW` and `DROP VIEW` only change metadata. 

### Syntax

```sql
CREATE [ OR REPLACE ] [ [ GLOBAL ] TEMPORARY ] VIEW [ IF NOT EXISTS ] view_identifier
    create_view_clauses AS query
```

### Parameters

* **OR REPLACE**

    If a view of same name already exists, it will be replaced.

* **[ GLOBAL ] TEMPORARY**

    TEMPORARY views are session-scoped and will be dropped when session ends
    because it skips persisting the definition in the underlying metastore, if any.
    GLOBAL TEMPORARY views are tied to a system preserved temporary database `global_temp`.

* **IF NOT EXISTS**

    Creates a view if it does not exist.

* **view_identifier**

    Specifies a view name, which may be optionally qualified with a database name.

    **Syntax:** `[ database_name. ] view_name`

* **create_view_clauses**

    These clauses are optional and order insensitive. It can be of following formats.

    * `[ ( column_name [ COMMENT column_comment ], ... ) ]` to specify column-level comments.
    * `[ COMMENT view_comment ]` to specify view-level comments.
    * `[ TBLPROPERTIES ( property_name = property_value [ , ... ] ) ]` to add metadata key-value pairs.

* **query**
  A [SELECT](sql-ref-syntax-qry-select.html) statement that constructs the view from base tables or other views.

### Examples

```sql
-- Create or replace view for `experienced_employee` with comments.
CREATE OR REPLACE VIEW experienced_employee
    (ID COMMENT 'Unique identification number', Name) 
    COMMENT 'View for experienced employees'
    AS SELECT id, name FROM all_employee
        WHERE working_years > 5;

-- Create a global temporary view `subscribed_movies` if it does not exist.
CREATE GLOBAL TEMPORARY VIEW IF NOT EXISTS subscribed_movies 
    AS SELECT mo.member_id, mb.full_name, mo.movie_title
        FROM movies AS mo INNER JOIN members AS mb 
        ON mo.member_id = mb.id;
```

### Related Statements

* [ALTER VIEW](sql-ref-syntax-ddl-alter-view.html)
* [DROP VIEW](sql-ref-syntax-ddl-drop-view.html)
* [SHOW VIEWS](sql-ref-syntax-aux-show-views.html)
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