DROP PROCEDURE
DROP PROCEDURE
DROP PROCEDURE - remove a procedure
Synopsis
DROP PROCEDURE [ IF EXISTS ]name
[ ( [ [argmode
] [argname
]argtype
[, ...] ] ) ] [, ...] [ CASCADE | RESTRICT ]
Description
DROP PROCEDURE
removes the definition of one or more
existing procedures. To execute this command the user must be the
owner of the procedure(s). The argument types to the
procedure(s) usually must be specified, since several different procedures
can exist with the same name and different argument lists.
Parameters
-
IF EXISTS
-
Do not throw an error if the procedure does not exist. A notice is issued in this case.
-
name
-
The name (optionally schema-qualified) of an existing procedure.
-
argmode
-
The mode of an argument:
IN
,OUT
,INOUT
, orVARIADIC
. If omitted, the default isIN
(but see below). -
argname
-
The name of an argument. Note that
DROP PROCEDURE
does not actually pay any attention to argument names, since only the argument data types are used to determine the procedure's identity. -
argtype
-
The data type(s) of the procedure's arguments (optionally schema-qualified), if any. See below for details.
-
CASCADE
-
Automatically drop objects that depend on the procedure, and in turn all objects that depend on those objects (see Section 5.14 ).
-
RESTRICT
-
Refuse to drop the procedure if any objects depend on it. This is the default.
Notes
If there is only one procedure of the given name, the argument list can be omitted. Omit the parentheses too in this case.
In
PostgreSQL
, it's sufficient to list the
input (including
INOUT
) arguments,
because no two routines of the same name are allowed to share the same
input-argument list. Moreover, the
DROP
command
will not actually check that you wrote the types
of
OUT
arguments correctly; so any arguments that
are explicitly marked
OUT
are just noise. But
writing them is recommendable for consistency with the
corresponding
CREATE
command.
For compatibility with the SQL standard, it is also allowed to write
all the argument data types (including those of
OUT
arguments) without
any
argmode
markers.
When this is done, the types of the procedure's
OUT
argument(s)
will
be verified against the command.
This provision creates an ambiguity, in that when the argument list
contains no
argmode
markers, it's unclear which rule is intended.
The
DROP
command will attempt the lookup both ways,
and will throw an error if two different procedures are found.
To avoid the risk of such ambiguity, it's recommendable to
write
IN
markers explicitly rather than letting them
be defaulted, thus forcing the
traditional
PostgreSQL
interpretation to be
used.
The lookup rules just explained are also used by other commands that
act on existing procedures, such as
ALTER PROCEDURE
and
COMMENT ON PROCEDURE
.
Examples
If there is only one procedure
do_db_maintenance
,
this command is sufficient to drop it:
DROP PROCEDURE do_db_maintenance;
Given this procedure definition:
CREATE PROCEDURE do_db_maintenance(IN target_schema text, OUT results text) ...
any one of these commands would work to drop it:
DROP PROCEDURE do_db_maintenance(IN target_schema text, OUT results text); DROP PROCEDURE do_db_maintenance(IN text, OUT text); DROP PROCEDURE do_db_maintenance(IN text); DROP PROCEDURE do_db_maintenance(text); DROP PROCEDURE do_db_maintenance(text, text); -- potentially ambiguous
However, the last example would be ambiguous if there is also, say,
CREATE PROCEDURE do_db_maintenance(IN target_schema text, IN options text) ...
Compatibility
This command conforms to the SQL standard, with these PostgreSQL extensions:
-
The standard only allows one procedure to be dropped per command.
-
The
IF EXISTS
option is an extension. -
The ability to specify argument modes and names is an extension, and the lookup rules differ when modes are given.