a75dc80a76
### What changes were proposed in this pull request? Remove the unneeded embedded inline HTML markup by using the basic markdown syntax. Please see #28414 ### Why are the changes needed? Make the doc cleaner and easily editable by MD editors. ### Does this PR introduce _any_ user-facing change? No ### How was this patch tested? Manually build and check Closes #28451 from huaxingao/html_cleanup. Authored-by: Huaxin Gao <huaxing@us.ibm.com> Signed-off-by: Sean Owen <srowen@gmail.com>
112 lines
5.1 KiB
Markdown
112 lines
5.1 KiB
Markdown
---
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layout: global
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title: DESCRIBE FUNCTION
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displayTitle: DESCRIBE FUNCTION
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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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`DESCRIBE FUNCTION` statement returns the basic metadata information of an
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existing function. The metadata information includes the function name, implementing
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class and the usage details. If the optional `EXTENDED` option is specified, the basic
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metadata information is returned along with the extended usage information.
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### Syntax
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```sql
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{ DESC | DESCRIBE } FUNCTION [ EXTENDED ] function_name
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```
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### Parameters
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* **function_name**
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Specifies a name of an existing function in the system. The function name may be
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optionally qualified with a database name. If `function_name` is qualified with
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a database then the function is resolved from the user specified database, otherwise
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it is resolved from the current database.
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**Syntax:** `[ database_name. ] function_name`
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### Examples
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```sql
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-- Describe a builtin scalar function.
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-- Returns function name, implementing class and usage
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DESC FUNCTION abs;
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+-------------------------------------------------------------------+
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|function_desc |
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+-------------------------------------------------------------------+
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|Function: abs |
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|Class: org.apache.spark.sql.catalyst.expressions.Abs |
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|Usage: abs(expr) - Returns the absolute value of the numeric value.|
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+-------------------------------------------------------------------+
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-- Describe a builtin scalar function.
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-- Returns function name, implementing class and usage and examples.
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DESC FUNCTION EXTENDED abs;
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+-------------------------------------------------------------------+
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|function_desc |
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+-------------------------------------------------------------------+
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|Function: abs |
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|Class: org.apache.spark.sql.catalyst.expressions.Abs |
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|Usage: abs(expr) - Returns the absolute value of the numeric value.|
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|Extended Usage: |
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| Examples: |
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| > SELECT abs(-1); |
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| 1 |
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+-------------------------------------------------------------------+
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-- Describe a builtin aggregate function
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DESC FUNCTION max;
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+--------------------------------------------------------------+
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|function_desc |
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+--------------------------------------------------------------+
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|Function: max |
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|Class: org.apache.spark.sql.catalyst.expressions.aggregate.Max|
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|Usage: max(expr) - Returns the maximum value of `expr`. |
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+--------------------------------------------------------------+
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-- Describe a builtin user defined aggregate function
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-- Returns function name, implementing class and usage and examples.
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DESC FUNCTION EXTENDED explode
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+---------------------------------------------------------------+
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|function_desc |
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+---------------------------------------------------------------+
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|Function: explode |
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|Class: org.apache.spark.sql.catalyst.expressions.Explode |
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|Usage: explode(expr) - Separates the elements of array `expr` |
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| into multiple rows, or the elements of map `expr` into |
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| multiple rows and columns. Unless specified otherwise, uses |
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| the default column name `col` for elements of the array or |
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| `key` and `value` for the elements of the map. |
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|Extended Usage: |
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| Examples: |
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| > SELECT explode(array(10, 20)); |
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| 10 |
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| 20 |
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+---------------------------------------------------------------+
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```
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### Related Statements
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* [DESCRIBE DATABASE](sql-ref-syntax-aux-describe-database.html)
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* [DESCRIBE TABLE](sql-ref-syntax-aux-describe-table.html)
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* [DESCRIBE QUERY](sql-ref-syntax-aux-describe-query.html)
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