Ubuntu Manpage: CREATE_PROCEDURE - define a new procedure

Provided by: postgresql-client-17_17.2-1_amd64

NAME

       CREATE_PROCEDURE - define a new procedure

SYNOPSIS

       CREATE [ OR REPLACE ] PROCEDURE
           name ( [ [ argmode ] [ argname ] argtype [ { DEFAULT | = } default_expr ] [, ...] ] )
         { LANGUAGE lang_name
           | TRANSFORM { FOR TYPE type_name } [, ... ]
           | [ EXTERNAL ] SECURITY INVOKER | [ EXTERNAL ] SECURITY DEFINER
           | SET configuration_parameter { TO value | = value | FROM CURRENT }
           | AS 'definition'
           | AS 'obj_file', 'link_symbol'
           | sql_body
         } ...

DESCRIPTION

CREATE PROCEDURE defines a new procedure. CREATE OR REPLACE PROCEDURE will either create
a new procedure, or replace an existing definition. To be able to define a procedure, the
user must have the USAGE privilege on the language.

If a schema name is included, then the procedure is created in the specified schema.
Otherwise it is created in the current schema. The name of the new procedure must not
match any existing procedure or function with the same input argument types in the same
schema. However, procedures and functions of different argument types can share a name
(this is called overloading).

To replace the current definition of an existing procedure, use CREATE OR REPLACE
PROCEDURE. It is not possible to change the name or argument types of a procedure this way
(if you tried, you would actually be creating a new, distinct procedure).

When CREATE OR REPLACE PROCEDURE is used to replace an existing procedure, the ownership
and permissions of the procedure do not change. All other procedure properties are
assigned the values specified or implied in the command. You must own the procedure to
replace it (this includes being a member of the owning role).

The user that creates the procedure becomes the owner of the procedure.

To be able to create a procedure, you must have USAGE privilege on the argument types.

Refer to Section 36.4 for further information on writing procedures.

PARAMETERS

name
The name (optionally schema-qualified) of the procedure to create.

argmode
The mode of an argument: IN, OUT, INOUT, or VARIADIC. If omitted, the default is IN.

argname
The name of an argument.

argtype
The data type(s) of the procedure's arguments (optionally schema-qualified), if any.
The argument types can be base, composite, or domain types, or can reference the type
of a table column.

Depending on the implementation language it might also be allowed to specify
“pseudo-types” such as cstring. Pseudo-types indicate that the actual argument type is
either incompletely specified, or outside the set of ordinary SQL data types.

The type of a column is referenced by writing table_name.column_name%TYPE. Using this
feature can sometimes help make a procedure independent of changes to the definition
of a table.

default_expr
An expression to be used as default value if the parameter is not specified. The
expression has to be coercible to the argument type of the parameter. All input
parameters following a parameter with a default value must have default values as
well.

lang_name
The name of the language that the procedure is implemented in. It can be sql, c,
internal, or the name of a user-defined procedural language, e.g., plpgsql. The
default is sql if sql_body is specified. Enclosing the name in single quotes is
deprecated and requires matching case.

TRANSFORM { FOR TYPE type_name } [, ... ] }
Lists which transforms a call to the procedure should apply. Transforms convert
between SQL types and language-specific data types; see CREATE TRANSFORM
(CREATE_TRANSFORM(7)). Procedural language implementations usually have hardcoded
knowledge of the built-in types, so those don't need to be listed here. If a
procedural language implementation does not know how to handle a type and no transform
is supplied, it will fall back to a default behavior for converting data types, but
this depends on the implementation.

[EXTERNAL] SECURITY INVOKER
[EXTERNAL] SECURITY DEFINER
SECURITY INVOKER indicates that the procedure is to be executed with the privileges of
the user that calls it. That is the default. SECURITY DEFINER specifies that the
procedure is to be executed with the privileges of the user that owns it.

The key word EXTERNAL is allowed for SQL conformance, but it is optional since, unlike
in SQL, this feature applies to all procedures not only external ones.

A SECURITY DEFINER procedure cannot execute transaction control statements (for
example, COMMIT and ROLLBACK, depending on the language).

configuration_parameter
value
The SET clause causes the specified configuration parameter to be set to the specified
value when the procedure is entered, and then restored to its prior value when the
procedure exits. SET FROM CURRENT saves the value of the parameter that is current
when CREATE PROCEDURE is executed as the value to be applied when the procedure is
entered.

If a SET clause is attached to a procedure, then the effects of a SET LOCAL command
executed inside the procedure for the same variable are restricted to the procedure:
the configuration parameter's prior value is still restored at procedure exit.
However, an ordinary SET command (without LOCAL) overrides the SET clause, much as it
would do for a previous SET LOCAL command: the effects of such a command will persist
after procedure exit, unless the current transaction is rolled back.

If a SET clause is attached to a procedure, then that procedure cannot execute
transaction control statements (for example, COMMIT and ROLLBACK, depending on the
language).

See SET(7) and Chapter 19 for more information about allowed parameter names and
values.

definition
A string constant defining the procedure; the meaning depends on the language. It can
be an internal procedure name, the path to an object file, an SQL command, or text in
a procedural language.

It is often helpful to use dollar quoting (see Section 4.1.2.4) to write the procedure
definition string, rather than the normal single quote syntax. Without dollar quoting,
any single quotes or backslashes in the procedure definition must be escaped by
doubling them.

obj_file, link_symbol
This form of the AS clause is used for dynamically loadable C language procedures when
the procedure name in the C language source code is not the same as the name of the
SQL procedure. The string obj_file is the name of the shared library file containing
the compiled C procedure, and is interpreted as for the LOAD command. The string
link_symbol is the procedure's link symbol, that is, the name of the procedure in the
C language source code. If the link symbol is omitted, it is assumed to be the same as
the name of the SQL procedure being defined.

When repeated CREATE PROCEDURE calls refer to the same object file, the file is only
loaded once per session. To unload and reload the file (perhaps during development),
start a new session.

sql_body
The body of a LANGUAGE SQL procedure. This should be a block

BEGIN ATOMIC
statement;
statement;
...
statement;
END

This is similar to writing the text of the procedure body as a string constant (see
definition above), but there are some differences: This form only works for LANGUAGE
SQL, the string constant form works for all languages. This form is parsed at
procedure definition time, the string constant form is parsed at execution time;
therefore this form cannot support polymorphic argument types and other constructs
that are not resolvable at procedure definition time. This form tracks dependencies
between the procedure and objects used in the procedure body, so DROP ... CASCADE will
work correctly, whereas the form using string literals may leave dangling procedures.
Finally, this form is more compatible with the SQL standard and other SQL
implementations.

NOTES

       See CREATE FUNCTION (CREATE_FUNCTION(7)) for more details on function creation that also
       apply to procedures.

       Use CALL(7) to execute a procedure.

EXAMPLES

           CREATE PROCEDURE insert_data(a integer, b integer)
           LANGUAGE SQL
           AS $$
           INSERT INTO tbl VALUES (a);
           INSERT INTO tbl VALUES (b);
           $$;

       or

           CREATE PROCEDURE insert_data(a integer, b integer)
           LANGUAGE SQL
           BEGIN ATOMIC
             INSERT INTO tbl VALUES (a);
             INSERT INTO tbl VALUES (b);
           END;

       and call like this:

           CALL insert_data(1, 2);

COMPATIBILITY

       A CREATE PROCEDURE command is defined in the SQL standard. The PostgreSQL implementation
       can be used in a compatible way but has many extensions. For details see also CREATE
       FUNCTION (CREATE_FUNCTION(7)).