Spark SQL Guide

SHOW FUNCTIONS

Description

Returns the list of functions after applying an optional regex pattern. Given number of functions supported by Spark is quite large, this statement in conjuction with describe function may be used to quickly find the function and understand its usage. The LIKE clause is optional and supported only for compatibility with other systems.

Syntax

SHOW [ function_kind ] FUNCTIONS ([LIKE] function_name | regex_pattern)

Parameters

function_kind
Specifies the name space of the function to be searched upon. The valid name spaces are :
  • USER - Looks up the function(s) among the user defined functions.
  • SYSTEM - Looks up the function(s) among the system defined functions.
  • ALL - Looks up the function(s) among both user and system defined functions.
function_name
Specifies a name of an existing function in the system. The function name may be optionally qualified with a database name. If `function_name` is qualified with a database then the function is resolved from the user specified database, otherwise it is resolved from the current database.

Syntax: [database_name.]function_name
regex_pattern
Specifies a regular expression pattern that is used to limit the results of the statement.
  • Only `*` and `|` are allowed as wildcard pattern.
  • Excluding `*` and `|` the remaining pattern follows the regex semantics.
  • The leading and trailing blanks are trimmed in the input pattern before processing.

Examples

-- List a system function `trim` by searching both user defined and system
-- defined functions.
SHOW FUNCTIONS trim;
  +--------+
  |function|
  +--------+
  |trim    |
  +--------+

-- List a system function `concat` by searching system defined functions.
SHOW SYSTEM FUNCTIONS concat;
  +--------+
  |function|
  +--------+
  |concat  |
  +--------+

-- List a qualified function `max` from database `salesdb`. 
SHOW SYSTEM FUNCTIONS salesdb.max;
  +--------+
  |function|
  +--------+
  |max     |
  +--------+

-- List all functions starting with `t`
SHOW FUNCTIONS LIKE 't*';
  +-----------------+
  |function         |
  +-----------------+
  |tan              |
  |tanh             |
  |timestamp        |
  |tinyint          |
  |to_csv           |
  |to_date          |
  |to_json          |
  |to_timestamp     |
  |to_unix_timestamp|
  |to_utc_timestamp |
  |transform        |
  |transform_keys   |
  |transform_values |
  |translate        |
  |trim             |
  |trunc            |
  +-----------------+

-- List all functions starting with `yea` or `windo`
SHOW FUNCTIONS LIKE 'yea*|windo*';
  +--------+
  |function|
  +--------+
  |window  |
  |year    |
  +--------+

-- Use normal regex pattern to list function names that has 4 characters
-- with `t` as the starting character.
SHOW FUNCTIONS LIKE 't[a-z][a-z][a-z]';
  +--------+
  |function|
  +--------+
  |tanh    |
  |trim    |
  +--------+