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SYSTEM CATALOGS / SYSTEM CATALOGS

The catalog pg_type stores information about data types.

Kind
System catalogs
Columns in this snapshot
32
Definition source
English manual

Columns 32

ColumnTypeDescription / reference
oidoidRow identifier
typnamenameData type name
typnamespaceoidThe OID of the namespace that contains this type
pg_namespace.oid
typowneroidOwner of the type
pg_authid.oid
typlenint2For 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.
typbyvalbooltypbyval 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 machines where Datum is 8 bytes). Variable-length types are always passed by reference. Note that typbyval can be false even if the length would allow pass-by-value.
typtypechartyptype is b for a base type, c for a composite type (e.g., a table's row type), d for a domain, e for an enum type, p for a pseudo-type, r for a range type, or m for a multirange type. See also typrelid and typbasetype.
typcategorychartypcategory is an arbitrary classification of data types that is used by the parser to determine which implicit casts should be “preferred”. See Table 52.65.
typispreferredboolTrue if the type is a preferred cast target within its typcategory
typisdefinedboolTrue if the type is defined, false if this is a placeholder entry for a not-yet-defined type. When typisdefined is false, nothing except the type name, namespace, and OID can be relied on.
typdelimcharCharacter 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.
typrelidoidIf this is a composite type (see typtype), then this column points to the pg_class entry that defines the corresponding table. (For a free-standing composite type, the pg_class entry doesn't really represent a table, but it is needed anyway for the type's pg_attribute entries to link to.) Zero for non-composite types.
pg_class.oid
typsubscriptregprocSubscripting handler function's OID, or zero if this type doesn't support subscripting. Types that are “true” array types have typsubscript = array_subscript_handler, but other types may have other handler functions to implement specialized subscripting behavior.
pg_proc.oid
typelemoidIf typelem is not zero then it identifies another row in pg_type, defining the type yielded by subscripting. This should be zero if typsubscript is zero. However, it can be zero when typsubscript isn't zero, if the handler doesn't need typelem to determine the subscripting result type. Note that a typelem dependency is considered to imply physical containment of the element type in this type; so DDL changes on the element type might be restricted by the presence of this type.
typarrayoidIf typarray is not zero then it identifies another row in pg_type, which is the “true” array type having this type as element
typinputregprocInput conversion function (text format)
pg_proc.oid
typoutputregprocOutput conversion function (text format)
pg_proc.oid
typreceiveregprocInput conversion function (binary format), or zero if none
pg_proc.oid
typsendregprocOutput conversion function (binary format), or zero if none
pg_proc.oid
typmodinregprocType modifier input function, or zero if type does not support modifiers
pg_proc.oid
typmodoutregprocType modifier output function, or zero to use the standard format
pg_proc.oid
typanalyzeregprocCustom ANALYZE function, or zero to use the standard function
pg_proc.oid
typalignchartypalign is 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 PostgreSQL. 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:
typstoragechartypstorage tells for varlena types (those with typlen = -1) if the type is prepared for toasting and what the default strategy for attributes of this type should be. Possible values are: x is the usual choice for toast-able types. Note that m values can also be moved out to secondary storage, but only as a last resort (e and x values are moved first).
typnotnullbooltypnotnull represents a not-null constraint on a type. Used for domains only.
typbasetypeoidIf this is a domain (see typtype), then typbasetype identifies the type that this one is based on. Zero if this type is not a domain.
typtypmodint4Domains 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.
typndimsint4typndims is the number of array dimensions for a domain over an array (that is, typbasetype is an array type). Zero for types other than domains over array types.
typcollationoidtypcollation specifies the collation of the type. If the type does not support collations, this will be zero. A base type that supports collations will have a nonzero value here, typically DEFAULT_COLLATION_OID. A domain over a collatable type can have a collation OID different from its base type's, if one was specified for the domain.
pg_collation.oid
typdefaultbinpg_node_treeIf typdefaultbin is not null, it is the nodeToString() representation of a default expression for the type. This is only used for domains.
typdefaulttexttypdefault is 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 can be fed to the type's input converter to produce a constant.
typaclaclitem[]Access privileges; see Section 5.8 for details
Column history across versions
Column9.09.19.29.39.49.59.61011121314151617181920
oid···
typname
typnamespace
typowner
typlen
typbyval
typtype
typcategory
typispreferred
typisdefined
typdelim
typrelid
typelem
typarray
typinput
typoutput
typreceive
typsend
typmodin
typmodout
typanalyze
typalign
typstorage
typnotnull
typbasetype
typtypmod
typndims
typcollation·
typdefaultbin
typdefault
typacl··
typsubscript···········
Version history 16
  1. PG 19 → 20changed
  2. PG 18 → 19changed
  3. PG 17 → 18changed
  4. PG 16 → 17changed
  5. PG 14 → 15changed
  6. PG 13 → 14changed
  7. PG 12 → 13changed
  8. PG 11 → 12changed
  9. PG 10 → 11changed
  10. PG 9.6 → 10changed
  11. PG 9.5 → 9.6changed
  12. PG 9.4 → 9.5changed
  13. PG 9.3 → 9.4changed
  14. PG 9.2 → 9.3changed
  15. PG 9.1 → 9.2changed
  16. PG 9.0 → 9.1changed

Definition snapshot: english-manuals:517c0954a945322f89b7efe35ee… · English manual source