internal

Indicates that a function accepts or returns a server-internal data type.

Reading PostgreSQL 18.6.

PG10–20 core source inventory. Casts and operator classes show explicitly declared relationships; absent rows do not rule out coercions or indexing through other mechanisms.

Definition

Indicates that a function accepts or returns a server-internal data type.

internal

Catalog name: pg_catalog.internal
Type OID: 2281
Type kind: Pseudo-type
Declared length: SIZEOF_POINTER (build constant)
Storage strategy: plain
Input function: internal_in
Output function: internal_out
Documented declaration: internal
Manual description: Indicates that a function accepts or returns a server-internal data type.

English manual

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Read the source definition

8.21. Pseudo-Types

The PostgreSQL type system contains a number of special-purpose entries that are collectively called pseudo-types. A pseudo-type cannot be used as a column data type, but it can be used to declare a function's argument or result type. Each of the available pseudo-types is useful in situations where a function's behavior does not correspond to simply taking or returning a value of a specific SQL data type. Table 8.27 lists the existing pseudo-types.

Table 8.27. Pseudo-Types

Name	Description
`any`	Indicates that a function accepts any input data type.
`anyelement`	Indicates that a function accepts any data type (see Section 36.2.5).
`anyarray`	Indicates that a function accepts any array data type (see Section 36.2.5).
`anynonarray`	Indicates that a function accepts any non-array data type (see Section 36.2.5).
`anyenum`	Indicates that a function accepts any enum data type (see Section 36.2.5 and Section 8.7).
`anyrange`	Indicates that a function accepts any range data type (see Section 36.2.5 and Section 8.17).
`anymultirange`	Indicates that a function accepts any multirange data type (see Section 36.2.5 and Section 8.17).
`anycompatible`	Indicates that a function accepts any data type, with automatic promotion of multiple arguments to a common data type (see Section 36.2.5).
`anycompatiblearray`	Indicates that a function accepts any array data type, with automatic promotion of multiple arguments to a common data type (see Section 36.2.5).
`anycompatiblenonarray`	Indicates that a function accepts any non-array data type, with automatic promotion of multiple arguments to a common data type (see Section 36.2.5).
`anycompatiblerange`	Indicates that a function accepts any range data type, with automatic promotion of multiple arguments to a common data type (see Section 36.2.5 and Section 8.17).
`anycompatiblemultirange`	Indicates that a function accepts any multirange data type, with automatic promotion of multiple arguments to a common data type (see Section 36.2.5 and Section 8.17).
`cstring`	Indicates that a function accepts or returns a null-terminated C string.
`internal`	Indicates that a function accepts or returns a server-internal data type.
`language_handler`	A procedural language call handler is declared to return `language_handler`.
`fdw_handler`	A foreign-data wrapper handler is declared to return `fdw_handler`.
`table_am_handler`	A table access method handler is declared to return `table_am_handler`.
`index_am_handler`	An index access method handler is declared to return `index_am_handler`.
`tsm_handler`	A tablesample method handler is declared to return `tsm_handler`.
`record`	Identifies a function taking or returning an unspecified row type.
`trigger`	A trigger function is declared to return `trigger.`
`event_trigger`	An event trigger function is declared to return `event_trigger.`
`pg_ddl_command`	Identifies a representation of DDL commands that is available to event triggers.
`void`	Indicates that a function returns no value.
`unknown`	Identifies a not-yet-resolved type, e.g., of an undecorated string literal.

Functions coded in C (whether built-in or dynamically loaded) can be declared to accept or return any of these pseudo-types. It is up to the function author to ensure that the function will behave safely when a pseudo-type is used as an argument type.

Functions coded in procedural languages can use pseudo-types only as allowed by their implementation languages. At present most procedural languages forbid use of a pseudo-type as an argument type, and allow only void and record as a result type (plus trigger or event_trigger when the function is used as a trigger or event trigger). Some also support polymorphic functions using the polymorphic pseudo-types, which are shown above and discussed in detail in Section 36.2.5.

The internal pseudo-type is used to declare functions that are meant only to be called internally by the database system, and not by direct invocation in an SQL query. If a function has at least one internal-type argument then it cannot be called from SQL. To preserve the type safety of this restriction it is important to follow this coding rule: do not create any function that is declared to return internal unless it has at least one internal argument.

Catalog attributes

Source bootstrap values for this build. See pg_type for field meanings. Header defaults are included; build-dependent constants remain symbolic. This is not a live-server measurement.

oid: 2281
descr: pseudo-type representing an internal data structure
typacl: _null_
typlen: SIZEOF_POINTER
typelem: 0
typname: internal
typsend: -
typtype: p
typalign: ALIGNOF_POINTER
typarray: 0
typbyval: t
typdelim: ','
typinput: internal_in
typmodin: -
typndims: 0
typowner: POSTGRES
typrelid: 0
typmodout: -
typoutput: internal_out
typtypmod: -1
typanalyze: -
typdefault: _null_
typnotnull: f
typreceive: -
typstorage: p
typbasetype: 0
typcategory: P
typcollation: 0
typisdefined: t
typnamespace: pg_catalog
typsubscript: -
typdefaultbin: _null_
array_type_oid: 0
typispreferred: f
array_type_name

Version comparison

PostgreSQL 17.11 → 18.6. Source build identifiers and prose are excluded from attribute changes.

No catalog or structured attribute changes between these samples.

The documentation also differs between these builds; inspect the versioned manual definitions.

Documentation and source

Build: 18.6 · https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2
Fingerprint: 555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f

Related entries

All Data Types · Download this version as JSON · The first recorded sample does not establish when a type was introduced.