1CREATE LANGUAGE(7) PostgreSQL 13.4 Documentation CREATE LANGUAGE(7)
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6 CREATE_LANGUAGE - define a new procedural language
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9 CREATE [ OR REPLACE ] [ TRUSTED ] [ PROCEDURAL ] LANGUAGE name
10 HANDLER call_handler [ INLINE inline_handler ] [ VALIDATOR valfunction ]
11 CREATE [ OR REPLACE ] [ TRUSTED ] [ PROCEDURAL ] LANGUAGE name
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14 CREATE LANGUAGE registers a new procedural language with a PostgreSQL
15 database. Subsequently, functions and procedures can be defined in this
16 new language.
17 CREATE LANGUAGE effectively associates the language name with handler
19 function(s) that are responsible for executing functions written in the
20 language. Refer to Chapter 55 for more information about language
21 handlers.
22 CREATE OR REPLACE LANGUAGE will either create a new language, or
24 replace an existing definition. If the language already exists, its
25 parameters are updated according to the command, but the language's
26 ownership and permissions settings do not change, and any existing
27 functions written in the language are assumed to still be valid.
28 One must have the PostgreSQL superuser privilege to register a new
30 language or change an existing language's parameters. However, once the
31 language is created it is valid to assign ownership of it to a
32 non-superuser, who may then drop it, change its permissions, rename it,
33 or assign it to a new owner. (Do not, however, assign ownership of the
34 underlying C functions to a non-superuser; that would create a
35 privilege escalation path for that user.)
36 The form of CREATE LANGUAGE that does not supply any handler function
38 is obsolete. For backwards compatibility with old dump files, it is
39 interpreted as CREATE EXTENSION. That will work if the language has
40 been packaged into an extension of the same name, which is the
41 conventional way to set up procedural languages.
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44 TRUSTED
45 TRUSTED specifies that the language does not grant access to data
46 that the user would not otherwise have. If this key word is omitted
47 when registering the language, only users with the PostgreSQL
48 superuser privilege can use this language to create new functions.
49 PROCEDURAL
51 This is a noise word.
52 name
54 The name of the new procedural language. The name must be unique
55 among the languages in the database.
56 For backward compatibility, the name can be enclosed by single
58 quotes.
59 HANDLER call_handler
61 call_handler is the name of a previously registered function that
62 will be called to execute the procedural language's functions. The
63 call handler for a procedural language must be written in a
64 compiled language such as C with version 1 call convention and
65 registered with PostgreSQL as a function taking no arguments and
66 returning the language_handler type, a placeholder type that is
67 simply used to identify the function as a call handler.
68 INLINE inline_handler
70 inline_handler is the name of a previously registered function that
71 will be called to execute an anonymous code block (DO(7) command)
72 in this language. If no inline_handler function is specified, the
73 language does not support anonymous code blocks. The handler
74 function must take one argument of type internal, which will be the
75 DO command's internal representation, and it will typically return
76 void. The return value of the handler is ignored.
77 VALIDATOR valfunction
79 valfunction is the name of a previously registered function that
80 will be called when a new function in the language is created, to
81 validate the new function. If no validator function is specified,
82 then a new function will not be checked when it is created. The
83 validator function must take one argument of type oid, which will
84 be the OID of the to-be-created function, and will typically return
85 void.
86 A validator function would typically inspect the function body for
88 syntactical correctness, but it can also look at other properties
89 of the function, for example if the language cannot handle certain
90 argument types. To signal an error, the validator function should
91 use the ereport() function. The return value of the function is
92 ignored.
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95 Use DROP LANGUAGE (DROP_LANGUAGE(7)) to drop procedural languages.
96 The system catalog pg_language (see Section 51.29) records information
98 about the currently installed languages. Also, the psql command \dL
99 lists the installed languages.
100 To create functions in a procedural language, a user must have the
102 USAGE privilege for the language. By default, USAGE is granted to
103 PUBLIC (i.e., everyone) for trusted languages. This can be revoked if
104 desired.
105 Procedural languages are local to individual databases. However, a
107 language can be installed into the template1 database, which will cause
108 it to be available automatically in all subsequently-created databases.
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111 A minimal sequence for creating a new procedural language is:
112 CREATE FUNCTION plsample_call_handler() RETURNS language_handler
114 AS '$libdir/plsample'
115 LANGUAGE C;
116 CREATE LANGUAGE plsample
117 HANDLER plsample_call_handler;
118 Typically that would be written in an extension's creation script, and
120 users would do this to install the extension:
121 CREATE EXTENSION plsample;
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125 CREATE LANGUAGE is a PostgreSQL extension.
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128 ALTER LANGUAGE (ALTER_LANGUAGE(7)), CREATE FUNCTION
129 (CREATE_FUNCTION(7)), DROP LANGUAGE (DROP_LANGUAGE(7)), GRANT(7),
130 REVOKE(7)
131PostgreSQL 13.4 2021 CREATE LANGUAGE(7)