CREATE FUNCTION

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The CREATE FUNCTION statement creates a user-defined function.

Note:

The CREATE FUNCTION statement performs a schema change. For more information about how online schema changes work in CockroachDB, see Online Schema Changes.

Required privileges

  • To define a function, a user must have CREATE privilege on the schema of the function.
  • To define a function with a user-defined type, a user must have USAGE privilege on the user-defined type.
  • To resolve a function, a user must have at least the USAGE privilege on the schema of the function.
  • To call a function, a user must have EXECUTE privilege on the function.
  • At function definition and execution time, a user must have privileges on all the objects referenced in the function body. Privileges on referenced objects can be revoked and later function calls can fail due to lack of permission.

If you grant EXECUTE privilege as a default privilege at the database level, newly created functions inherit that privilege from the database.

Synopsis

CREATE OR REPLACE FUNCTION func_create_name ( func_arg , ) RETURNS func_arg_type AS SCONST LANGUAGE SQL CALLED RETURNS NULL ON NULL INPUT STRICT IMMUTABLE STABLE VOLATILE NOT LEAKPROOF opt_routine_body

Parameters

Parameter Description
func_create_name The name of the function.
func_arg A function argument.
func_arg_type The type returned by the function.
opt_routine_body The body of the function. For allowed contents, see User-Defined Functions: Overview.

Example of a simple function

The following statement creates a function to compute the square of integers:

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> CREATE OR REPLACE FUNCTION sq(a INT) RETURNS INT AS 'SELECT a*a' LANGUAGE SQL;

The following statement invokes the sq function:

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> SELECT sq(2);
  sq
-----
  4
(1 row)

Examples of functions that reference tables

Setup

The following examples use MovR, a fictional vehicle-sharing application, to demonstrate CockroachDB SQL statements. For more information about the MovR example application and dataset, see MovR: A Global Vehicle-sharing App.

To follow along, run cockroach demo to start a temporary, in-memory cluster with the movr dataset preloaded:

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$ cockroach demo

Create a function that references a table

The following statement defines a function that returns the total number of MovR application users.

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> CREATE OR REPLACE FUNCTION num_users() RETURNS INT AS 'SELECT count(*) from users' LANGUAGE SQL;
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> SELECT num_users();
  num_users
-------------
         50
(1 row)

Create a function that uses a WHERE clause

The following statement defines a function that returns the total revenue for rides taken in European cities.

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> CREATE OR REPLACE FUNCTION total_euro_revenue() RETURNS DECIMAL LANGUAGE SQL AS $$
  SELECT SUM(revenue) FROM rides WHERE city IN ('paris', 'rome', 'amsterdam')
  $$;
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> SELECT total_euro_revenue();
  total_euro_revenue
----------------------
             8468.00

See also


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