CREATE PROCEDURE — define a new procedure
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
  } ...
   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.
nameThe 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.
      
argnameThe name of an argument.
argtypeThe 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
default_exprAn 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. 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 DEFINERSECURITY 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_parametervalue
       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 and Chapter 19 for more information about allowed parameter names and values.
definitionA 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 ATOMICstatement;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.
      
See CREATE FUNCTION for more details on function creation that also apply to procedures.
Use CALL to execute a procedure.
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);
   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.