pg_type

The pg_type system catalog table stores information about data types. Base types (scalar types) are created with CREATE TYPE, and domains with CREATE DOMAIN. A composite type is automatically created for each table in the database to represent the row structure of the table. It is also possible to create composite types with CREATE TYPE AS.

Column Type References Description

Column	Type	References	Description
oid	oid	—	Row identifier (hidden attribute; must be explicitly selected)
typname	name	—	Data type name
typnamespace	oid	pg_namespace.oid	The OID of the namespace that contains this type
typowner	oid	pg_authid.oid	Owner of the type
typlen	int2	—	For a fixed-size type, `typlen` is the number of bytes in the internal representation of the type. But for a variable-length type, `typlen` is negative. `-1` indicates a `varlena` type (one that has a length word), `-2` indicates a `NULL`-terminated C string
typbyval	boolean	—	Determines whether internal routines pass a value of this type by value or by reference. `typbyval` had better be `false` if `typlen` is not 1, 2, or 4 (or 8, on 64-bit machines). Variable-length types are always passed by reference. Note that `typbyval` can be `false` even if the length allows pass-by-value
typtype	char	—	`b` — base type `c` — composite type `d` — domain `e` — enum type `p` — pseudo-type `r` — range type See also `typrelid` and `typbasetype`
typcategory	char	—	Arbitrary classification of data types that is used by the parser to determine which implicit casts should be preferred. See category codes
typispreferred	boolean	—	`true` if the type is a preferred cast target within its `typcategory`
typisdefined	boolean	—	`true` if the type is defined, `false` if this is a placeholder entry for a not-yet-defined type. When `false`, nothing except the type name, namespace, and OID can be relied on
typdelim	char	—	Character that separates two values of this type when parsing array input. Note that the delimiter is associated with the array element data type, not the array data type
typrelid	oid	pg_class.oid	If this is a composite type (see `typtype`), then this column points to the `pg_class` entry that defines the corresponding table. For a freestanding composite type, the `pg_class` entry does not really represent a table, but it is necessary anyway for the type’s `pg_attribute` entries to link to. `0` for non-composite types
typelem	oid	pg_type.oid	If not `0` then it identifies another row in `pg_type`. The current type can then be subscripted like an array yielding values of type `typelem`. A "true" array type is variable length (`typlen` = `-1`), but some fixed-length (`typlen` > `0`) types also have nonzero `typelem`, for example `name` and `point`. If a fixed-length type has a `typelem` then its internal representation must be some number of values of the `typelem` data type with no other data. Variable-length array types have a header defined by the array subroutines
typarray	oid	pg_type.oid	If not `0`, identifies another row in `pg_type`, which is the "true" array type having this type as its element. Use `pg_type.typarray` to locate the array type associated with a specific type
typinput	regproc	pg_proc.oid	Input conversion function (text format)
typoutput	regproc	pg_proc.oid	Output conversion function (text format)
typreceive	regproc	pg_proc.oid	Input conversion function (binary format), or `0` if none
typsend	regproc	pg_proc.oid	Output conversion function (binary format), or `0` if none
typmodin	regproc	pg_proc.oid	Type modifier input function, or `0` if the type does not support modifiers
typmodout	regproc	pg_proc.oid	Type modifier output function, or `0` to use the standard format
typanalyze	regproc	pg_proc.oid	Custom `ANALYZE` function, or `0` to use the standard function
typalign	char	—	The alignment required when storing a value of this type. It applies to storage on disk as well as most representations of the value inside Greengage DB. When multiple values are stored consecutively, such as in the representation of a complete row on disk, padding is inserted before a datum of this type so that it begins on the specified boundary. The alignment reference is the beginning of the first datum in the sequence. Possible values are: `c` — char alignment (no alignment needed). `s` — short alignment (2 bytes on most machines). `i` — int alignment (4 bytes on most machines). `d` — double alignment (8 bytes on many machines, but not all).
typstorage	char	—	For `varlena` types (those with `typlen` = -1) tells if the type is prepared for toasting and what the default strategy for attributes of this type should be. Possible values are: `p` — value must always be stored plain. `e` — value can be stored in a secondary relation (if relation has one, see `pg_class.reltoastrelid`). `m` — value can be stored compressed inline. `x` — value can be stored compressed inline or stored in secondary storage. Note that `m` columns can also be moved out to secondary storage, but only as a last resort (`e` and `x` columns are moved first)
typnotnull	boolean	—	Represents a not-null constraint on a type. Used for domains only
typbasetype	oid	pg_type.oid	Identifies the type that a domain is based on. `0` if this type is not a domain
typtypmod	integer	—	Domains use `typtypmod` to record the `typmod` to be applied to their base type (`-1` if base type does not use a `typmod`). `-1` if this type is not a domain
typndims	integer	—	The number of array dimensions for a domain over an array (if `typbasetype` is an array type). `0` for types other than domains over array types
typcollation	oid	pg_collation.oid	Specifies the collation of the type. `0` if the type does not support collations. The value is `DEFAULT_COLLATION_OID` for a base type that supports collations. A domain over a collatable type can have some other collation OID if one was specified for the domain
typdefaultbin	pg_node_tree	—	If not `NULL`, it is the `nodeToString()` representation of a default expression for the type. This is only used for domains
typdefault	text	—	`NULL` if the type has no associated default value. If `typdefaultbin` is not `NULL`, `typdefault` must contain a human-readable version of the default expression represented by `typdefaultbin`. If `typdefaultbin` is `NULL` and `typdefault` is not, then `typdefault` is the external representation of the type’s default value, which may be fed to the type’s input converter to produce a constant
typacl	aclitem[]	—	Access privileges (see Roles and privileges)

oid

—

Row identifier (hidden attribute; must be explicitly selected)

typname

name

—

Data type name

typnamespace

oid

pg_namespace.oid

The OID of the namespace that contains this type

typowner

oid

pg_authid.oid

Owner of the type

typlen

int2

—

For a fixed-size type, typlen is the number of bytes in the internal representation of the type. But for a variable-length type, typlen is negative. -1 indicates a varlena type (one that has a length word), -2 indicates a NULL-terminated C string

typbyval

boolean

—

Determines whether internal routines pass a value of this type by value or by reference. typbyval had better be false if typlen is not 1, 2, or 4 (or 8, on 64-bit machines). Variable-length types are always passed by reference. Note that typbyval can be false even if the length allows pass-by-value

typtype

char

—

b — base type
c — composite type
d — domain
e — enum type
p — pseudo-type
r — range type

See also typrelid and typbasetype

typcategory

char

—

Arbitrary classification of data types that is used by the parser to determine which implicit casts should be preferred. See category codes

typispreferred

boolean

—

true if the type is a preferred cast target within its typcategory

typisdefined

boolean

—

true if the type is defined, false if this is a placeholder entry for a not-yet-defined type. When false, nothing except the type name, namespace, and OID can be relied on

typdelim

char

—

Character that separates two values of this type when parsing array input. Note that the delimiter is associated with the array element data type, not the array data type

typrelid

oid

pg_class.oid

If this is a composite type (see typtype), then this column points to the pg_class entry that defines the corresponding table. For a freestanding composite type, the pg_class entry does not really represent a table, but it is necessary anyway for the type’s pg_attribute entries to link to. 0 for non-composite types

typelem

oid

pg_type.oid

If not 0 then it identifies another row in pg_type. The current type can then be subscripted like an array yielding values of type typelem. A "true" array type is variable length (typlen = -1), but some fixed-length (typlen > 0) types also have nonzero typelem, for example name and point. If a fixed-length type has a typelem then its internal representation must be some number of values of the typelem data type with no other data. Variable-length array types have a header defined by the array subroutines

typarray

oid

pg_type.oid

If not 0, identifies another row in pg_type, which is the "true" array type having this type as its element. Use pg_type.typarray to locate the array type associated with a specific type

typinput

regproc

pg_proc.oid

Input conversion function (text format)

typoutput

regproc

pg_proc.oid

Output conversion function (text format)

typreceive

regproc

pg_proc.oid

Input conversion function (binary format), or 0 if none

typsend

regproc

pg_proc.oid

Output conversion function (binary format), or 0 if none

typmodin

regproc

pg_proc.oid

Type modifier input function, or 0 if the type does not support modifiers

typmodout

regproc

pg_proc.oid

Type modifier output function, or 0 to use the standard format

typanalyze

regproc

pg_proc.oid

Custom ANALYZE function, or 0 to use the standard function

typalign

char

—

The alignment required when storing a value of this type. It applies to storage on disk as well as most representations of the value inside Greengage DB. When multiple values are stored consecutively, such as in the representation of a complete row on disk, padding is inserted before a datum of this type so that it begins on the specified boundary. The alignment reference is the beginning of the first datum in the sequence. Possible values are:

c — char alignment (no alignment needed).
s — short alignment (2 bytes on most machines).
i — int alignment (4 bytes on most machines).
d — double alignment (8 bytes on many machines, but not all).

typstorage

char

—

For varlena types (those with typlen = -1) tells if the type is prepared for toasting and what the default strategy for attributes of this type should be. Possible values are:

p — value must always be stored plain.
e — value can be stored in a secondary relation (if relation has one, see pg_class.reltoastrelid).
m — value can be stored compressed inline.
x — value can be stored compressed inline or stored in secondary storage.

Note that m columns can also be moved out to secondary storage, but only as a last resort (e and x columns are moved first)

typnotnull

boolean

—

Represents a not-null constraint on a type. Used for domains only

typbasetype

oid

pg_type.oid

Identifies the type that a domain is based on. 0 if this type is not a domain

typtypmod

integer

—

Domains use typtypmod to record the typmod to be applied to their base type (-1 if base type does not use a typmod). -1 if this type is not a domain

typndims

integer

—

The number of array dimensions for a domain over an array (if typbasetype is an array type). 0 for types other than domains over array types

typcollation

oid

pg_collation.oid

Specifies the collation of the type. 0 if the type does not support collations. The value is DEFAULT_COLLATION_OID for a base type that supports collations. A domain over a collatable type can have some other collation OID if one was specified for the domain

typdefaultbin

pg_node_tree

—

If not NULL, it is the nodeToString() representation of a default expression for the type. This is only used for domains

typdefault

text

—

NULL if the type has no associated default value. If typdefaultbin is not NULL, typdefault must contain a human-readable version of the default expression represented by typdefaultbin. If typdefaultbin is NULL and typdefault is not, then typdefault is the external representation of the type’s default value, which may be fed to the type’s input converter to produce a constant

typacl

aclitem[]

—

Access privileges (see Roles and privileges)

The following table lists the system-defined values of typcategory. Any future additions to this list will also be upper-case ASCII letters. All other ASCII characters are reserved for user-defined categories.

Code Category

Code	Category
A	Array types
B	boolean types
C	Composite types
D	Date/time types
E	Enum types
G	Geometric types
I	Network address types
N	Numeric types
P	Pseudo-types
R	Range types
S	String types
T	Timespan types
U	User-defined types
V	Bit-string types
X	`unknown` type

Array types

boolean types

Composite types

Date/time types

Enum types

Geometric types

Network address types

Numeric types

Pseudo-types

Range types

String types

Timespan types

User-defined types

Bit-string types

unknown type

pg_trigger

pg_type_encoding