ALTER_FUNCTION(7pg15)

📦 version 15.19, in opensuse-leap 16.0

💅 ALTER FUNCTION (7pg15) — the glow-up page

okay bestie, so this is the ALTER FUNCTION(7) page from the PostgreSQL 15.19 Documentation, and it's literally all about giving your existing function a makeover ✨ no cap, every flag is still here, we're just making it cute.

🌸 NAME 🌸

ALTER_FUNCTION — change the definition of a function 🫶

✨ SYNOPSIS ✨

ALTER FUNCTION name [ ( [ [ argmode ] [ argname ] argtype [, ...] ] ) ]
    action [ ... ] [ RESTRICT ]
ALTER FUNCTION name [ ( [ [ argmode ] [ argname ] argtype [, ...] ] ) ]
    RENAME TO new_name
ALTER FUNCTION name [ ( [ [ argmode ] [ argname ] argtype [, ...] ] ) ]
    OWNER TO { new_owner | CURRENT_ROLE | CURRENT_USER | SESSION_USER }
ALTER FUNCTION name [ ( [ [ argmode ] [ argname ] argtype [, ...] ] ) ]
    SET SCHEMA new_schema
ALTER FUNCTION name [ ( [ [ argmode ] [ argname ] argtype [, ...] ] ) ]
    [ NO ] DEPENDS ON EXTENSION extension_name

where action is one of:

CALLED ON NULL INPUT | RETURNS NULL ON NULL INPUT | STRICT
IMMUTABLE | STABLE | VOLATILE
[ NOT ] LEAKPROOF
[ EXTERNAL ] SECURITY INVOKER | [ EXTERNAL ] SECURITY DEFINER
PARALLEL { UNSAFE | RESTRICTED | SAFE }
COST execution_cost
ROWS result_rows
SUPPORT support_function
SET configuration_parameter { TO | = } { value | DEFAULT }
SET configuration_parameter FROM CURRENT
RESET configuration_parameter
RESET ALL

like, that's the whole menu, and every single line of it is a valid little vibe 💖

🦋 DESCRIPTION 🦋

ALTER FUNCTION changes the definition of a function. that's it, that's the tweet 💅

You must own the function to use ALTER FUNCTION. and bestie, if you're changing a function's schema, you also need CREATE privilege on the new schema. and to alter the owner? you must also be a direct or indirect member of the new owning role, and that role must have CREATE privilege on the function's schema. (these restrictions enforce that altering the owner doesn't do anything you couldn't do by dropping and recreating the function. however — plot twist — a superuser can alter ownership of any function anyway 👑)

so yeah, permissions are giving strict-parent energy, but that's literally for your own good 🫶

🎀 PARAMETERS 🎀

  • name — the name (optionally schema-qualified) of an existing function. if no argument list is specified, the name must be unique in its schema. no duplicates, periodt ✨
  • argmode — the mode of an argument: IN, OUT, INOUT, or VARIADIC. if omitted, the default is IN. note that ALTER FUNCTION does not actually pay any attention to OUT arguments, since only the input arguments are needed to determine the function's identity. so it is sufficient to list the IN, INOUT, and VARIADIC arguments. like, OUT is lowkey just there for the vibes 🙈
  • argname — the name of an argument. note that ALTER FUNCTION does not actually pay any attention to argument names, since only the argument data types are needed to determine the function's identity. names are cute but irrelevant here, iykyk 🎀
  • argtype — the data type(s) of the function's arguments (optionally schema-qualified), if any.
  • new_name — the new name of the function. rebranding era 💖
  • new_owner — the new owner of the function. note that if the function is marked SECURITY DEFINER, it will subsequently execute as the new owner. main character transfer, no cap 👑
  • new_schema — the new schema for the function.
  • DEPENDS ON EXTENSION extension_name
  • NO DEPENDS ON EXTENSION extension_name — this form marks the function as dependent on the extension, or no longer dependent on that extension if NO is specified. a function that's marked as dependent on an extension is dropped when the extension is dropped, even if CASCADE is not specified. a function can depend upon multiple extensions, and will be dropped when any one of those extensions is dropped. so like, attachment issues but make it SQL 😭💀
  • CALLED ON NULL INPUT
  • RETURNS NULL ON NULL INPUT
  • STRICT — CALLED ON NULL INPUT changes the function so that it will be invoked when some or all of its arguments are null. RETURNS NULL ON NULL INPUT or STRICT changes the function so that it is not invoked if any of its arguments are null; instead, a null result is assumed automatically. see CREATE FUNCTION (CREATE_FUNCTION(7)) for more information. null handling is literally a whole personality trait 🌸
  • IMMUTABLE
  • STABLE
  • VOLATILE — change the volatility of the function to the specified setting. see CREATE FUNCTION (CREATE_FUNCTION(7)) for details. pick your vibe: steady icon, stable queen, or chaotic volatile fairy 🧚
  • [ EXTERNAL ] SECURITY INVOKER
  • [ EXTERNAL ] SECURITY DEFINER — change whether the function is a security definer or not. the key word EXTERNAL is ignored for SQL conformance. see CREATE FUNCTION (CREATE_FUNCTION(7)) for more information about this capability. EXTERNAL is just there for the standards girlies 💅
  • PARALLEL — change whether the function is deemed safe for parallelism. see CREATE FUNCTION (CREATE_FUNCTION(7)) for details. can it run with the group chat or does it need solo time? 🌈
  • LEAKPROOF — change whether the function is considered leakproof or not. see CREATE FUNCTION (CREATE_FUNCTION(7)) for more information about this capability. no leaks bestie, we're sealed tight 🫶
  • COST execution_cost — change the estimated execution cost of the function. see CREATE FUNCTION (CREATE_FUNCTION(7)) for more information. budget era 💸
  • ROWS result_rows — change the estimated number of rows returned by a set-returning function. see CREATE FUNCTION (CREATE_FUNCTION(7)) for more information. manifest that row count ✨
  • SUPPORT support_function — set or change the planner support function to use for this function. see Section 38.11 for details. you must be superuser to use this option. 👑

this option cannot be used to remove the support function altogether, since it must name a new support function. use CREATE OR REPLACE FUNCTION if you need to do that. so like, you can swap the support function but you can't just leave it on read, sorry 💀

  • configuration_parameter
  • value — add or change the assignment to be made to a configuration parameter when the function is called. if value is DEFAULT or, equivalently, RESET is used, the function-local setting is removed, so that the function executes with the value present in its environment. use RESET ALL to clear all function-local settings. SET FROM CURRENT saves the value of the parameter that is current when ALTER FUNCTION is executed as the value to be applied when the function is entered.

see SET(7) and Chapter 20 for more information about allowed parameter names and values. that's the deep lore, go read it if you're obsessed 📚

  • RESTRICT — ignored for conformance with the SQL standard. it's literally just standing there, being decorative 🎀

💖 EXAMPLES 💖

To rename the function sqrt for type integer to square_root:

ALTER FUNCTION sqrt(integer) RENAME TO square_root;

To change the owner of the function sqrt for type integer to joe:

ALTER FUNCTION sqrt(integer) OWNER TO joe;

To change the schema of the function sqrt for type integer to maths:

ALTER FUNCTION sqrt(integer) SET SCHEMA maths;

To mark the function sqrt for type integer as being dependent on the extension mathlib:

ALTER FUNCTION sqrt(integer) DEPENDS ON EXTENSION mathlib;

To adjust the search path that is automatically set for a function:

ALTER FUNCTION check_password(text) SET search_path = admin, pg_temp;

To disable automatic setting of search_path for a function:

ALTER FUNCTION check_password(text) RESET search_path;

the function will now execute with whatever search path is used by its caller. and that's on autonomy ✨

🧚 COMPATIBILITY 🧚

this statement is partially compatible with the ALTER FUNCTION statement in the SQL standard. the standard allows more properties of a function to be modified, but does not provide the ability to rename a function, make a function a security definer, attach configuration parameter values to a function, or change the owner, schema, or volatility of a function. the standard also requires the RESTRICT key word, which is optional in PostgreSQL.

so like, SQL standard is the strict older sibling and PostgreSQL is the chill one who still ate 💅

👑 SEE ALSO 👑

and that's the page, bestie 🫶 this was PostgreSQL 15.19, dated 2026, footer energy and all — now go alter something iconic ✨💖🎀

📦 where this page comes from