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><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="CATALOG-PG-TYPE"
>44.41. <TT
CLASS="STRUCTNAME"
>pg_type</TT
></A
></H1
><A
NAME="AEN71841"
></A
><P
> The catalog <TT
CLASS="STRUCTNAME"
>pg_type</TT
> stores information about data
types. Base types (scalar types) are created with
<A
HREF="sql-createtype.html"
><I
>CREATE TYPE</I
></A
>, and
domains with
<A
HREF="sql-createdomain.html"
><I
>CREATE DOMAIN</I
></A
>.
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 <TT
CLASS="COMMAND"
>CREATE TYPE AS</TT
>.
</P
><DIV
CLASS="TABLE"
><A
NAME="AEN71848"
></A
><P
><B
>Table 44-41. <TT
CLASS="STRUCTNAME"
>pg_type</TT
> Columns</B
></P
><TABLE
BORDER="1"
CLASS="CALSTABLE"
><COL><COL><COL><COL><THEAD
><TR
><TH
>Name</TH
><TH
>Type</TH
><TH
>References</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>typname</TT
></TD
><TD
><TT
CLASS="TYPE"
>name</TT
></TD
><TD
> </TD
><TD
>Data type name</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>typnamespace</TT
></TD
><TD
><TT
CLASS="TYPE"
>oid</TT
></TD
><TD
><TT
CLASS="LITERAL"
><A
HREF="catalog-pg-namespace.html"
><TT
CLASS="STRUCTNAME"
>pg_namespace</TT
></A
>.oid</TT
></TD
><TD
> The OID of the namespace that contains this type
</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>typowner</TT
></TD
><TD
><TT
CLASS="TYPE"
>oid</TT
></TD
><TD
><TT
CLASS="LITERAL"
><A
HREF="catalog-pg-authid.html"
><TT
CLASS="STRUCTNAME"
>pg_authid</TT
></A
>.oid</TT
></TD
><TD
>Owner of the type</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>typlen</TT
></TD
><TD
><TT
CLASS="TYPE"
>int2</TT
></TD
><TD
> </TD
><TD
> For a fixed-size type, <TT
CLASS="STRUCTFIELD"
>typlen</TT
> is the number
of bytes in the internal representation of the type. But for a
variable-length type, <TT
CLASS="STRUCTFIELD"
>typlen</TT
> is negative.
-1 indicates a <SPAN
CLASS="QUOTE"
>"varlena"</SPAN
> type (one that has a length word),
-2 indicates a null-terminated C string.
</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>typbyval</TT
></TD
><TD
><TT
CLASS="TYPE"
>bool</TT
></TD
><TD
> </TD
><TD
> <TT
CLASS="STRUCTFIELD"
>typbyval</TT
> determines whether internal
routines pass a value of this type by value or by reference.
<TT
CLASS="STRUCTFIELD"
>typbyval</TT
> had better be false if
<TT
CLASS="STRUCTFIELD"
>typlen</TT
> 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
<TT
CLASS="STRUCTFIELD"
>typbyval</TT
> can be false even if the
length would allow pass-by-value; this is currently true for
type <TT
CLASS="TYPE"
>float4</TT
>, for example
</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>typtype</TT
></TD
><TD
><TT
CLASS="TYPE"
>char</TT
></TD
><TD
> </TD
><TD
> <TT
CLASS="STRUCTFIELD"
>typtype</TT
> is
<TT
CLASS="LITERAL"
>b</TT
> for a base type,
<TT
CLASS="LITERAL"
>c</TT
> for a composite type (e.g., a table's row type),
<TT
CLASS="LITERAL"
>d</TT
> for a domain,
<TT
CLASS="LITERAL"
>e</TT
> for an enum type,
or <TT
CLASS="LITERAL"
>p</TT
> for a pseudo-type.
See also <TT
CLASS="STRUCTFIELD"
>typrelid</TT
> and
<TT
CLASS="STRUCTFIELD"
>typbasetype</TT
>
</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>typisdefined</TT
></TD
><TD
><TT
CLASS="TYPE"
>bool</TT
></TD
><TD
> </TD
><TD
> True if the type is defined, false if this is a placeholder
entry for a not-yet-defined type. When
<TT
CLASS="STRUCTFIELD"
>typisdefined</TT
> is false, nothing
except the type name, namespace, and OID can be relied on
</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>typdelim</TT
></TD
><TD
><TT
CLASS="TYPE"
>char</TT
></TD
><TD
> </TD
><TD
> 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
</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>typrelid</TT
></TD
><TD
><TT
CLASS="TYPE"
>oid</TT
></TD
><TD
><TT
CLASS="LITERAL"
><A
HREF="catalog-pg-class.html"
><TT
CLASS="STRUCTNAME"
>pg_class</TT
></A
>.oid</TT
></TD
><TD
> If this is a composite type (see
<TT
CLASS="STRUCTFIELD"
>typtype</TT
>), then this column points to
the <TT
CLASS="STRUCTNAME"
>pg_class</TT
> entry that defines the
corresponding table. (For a free-standing composite type, the
<TT
CLASS="STRUCTNAME"
>pg_class</TT
> entry doesn't really represent
a table, but it is needed anyway for the type's
<TT
CLASS="STRUCTNAME"
>pg_attribute</TT
> entries to link to.)
Zero for non-composite types
</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>typelem</TT
></TD
><TD
><TT
CLASS="TYPE"
>oid</TT
></TD
><TD
><TT
CLASS="LITERAL"
><A
HREF="catalog-pg-type.html"
><TT
CLASS="STRUCTNAME"
>pg_type</TT
></A
>.oid</TT
></TD
><TD
> If <TT
CLASS="STRUCTFIELD"
>typelem</TT
> is not 0 then it
identifies another row in <TT
CLASS="STRUCTNAME"
>pg_type</TT
>.
The current type can then be subscripted like an array yielding
values of type <TT
CLASS="STRUCTFIELD"
>typelem</TT
>. A
<SPAN
CLASS="QUOTE"
>"true"</SPAN
> array type is variable length
(<TT
CLASS="STRUCTFIELD"
>typlen</TT
> = -1),
but some fixed-length (<TT
CLASS="STRUCTFIELD"
>typlen</TT
> > 0) types
also have nonzero <TT
CLASS="STRUCTFIELD"
>typelem</TT
>, for example
<TT
CLASS="TYPE"
>name</TT
> and <TT
CLASS="TYPE"
>point</TT
>.
If a fixed-length type has a <TT
CLASS="STRUCTFIELD"
>typelem</TT
> then
its internal representation must be some number of values of the
<TT
CLASS="STRUCTFIELD"
>typelem</TT
> data type with no other data.
Variable-length array types have a header defined by the array
subroutines
</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>typarray</TT
></TD
><TD
><TT
CLASS="TYPE"
>oid</TT
></TD
><TD
><TT
CLASS="LITERAL"
><A
HREF="catalog-pg-type.html"
><TT
CLASS="STRUCTNAME"
>pg_type</TT
></A
>.oid</TT
></TD
><TD
> If <TT
CLASS="STRUCTFIELD"
>typarray</TT
> is not 0 then it
identifies another row in <TT
CLASS="STRUCTNAME"
>pg_type</TT
>, which
is the <SPAN
CLASS="QUOTE"
>"true"</SPAN
> array type having this type as element
</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>typinput</TT
></TD
><TD
><TT
CLASS="TYPE"
>regproc</TT
></TD
><TD
><TT
CLASS="LITERAL"
><A
HREF="catalog-pg-proc.html"
><TT
CLASS="STRUCTNAME"
>pg_proc</TT
></A
>.oid</TT
></TD
><TD
>Input conversion function (text format)</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>typoutput</TT
></TD
><TD
><TT
CLASS="TYPE"
>regproc</TT
></TD
><TD
><TT
CLASS="LITERAL"
><A
HREF="catalog-pg-proc.html"
><TT
CLASS="STRUCTNAME"
>pg_proc</TT
></A
>.oid</TT
></TD
><TD
>Output conversion function (text format)</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>typreceive</TT
></TD
><TD
><TT
CLASS="TYPE"
>regproc</TT
></TD
><TD
><TT
CLASS="LITERAL"
><A
HREF="catalog-pg-proc.html"
><TT
CLASS="STRUCTNAME"
>pg_proc</TT
></A
>.oid</TT
></TD
><TD
>Input conversion function (binary format), or 0 if none</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>typsend</TT
></TD
><TD
><TT
CLASS="TYPE"
>regproc</TT
></TD
><TD
><TT
CLASS="LITERAL"
><A
HREF="catalog-pg-proc.html"
><TT
CLASS="STRUCTNAME"
>pg_proc</TT
></A
>.oid</TT
></TD
><TD
>Output conversion function (binary format), or 0 if none</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>typmodin</TT
></TD
><TD
><TT
CLASS="TYPE"
>regproc</TT
></TD
><TD
><TT
CLASS="LITERAL"
><A
HREF="catalog-pg-proc.html"
><TT
CLASS="STRUCTNAME"
>pg_proc</TT
></A
>.oid</TT
></TD
><TD
>Type modifier input function, or 0 if type does not support modifiers</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>typmodout</TT
></TD
><TD
><TT
CLASS="TYPE"
>regproc</TT
></TD
><TD
><TT
CLASS="LITERAL"
><A
HREF="catalog-pg-proc.html"
><TT
CLASS="STRUCTNAME"
>pg_proc</TT
></A
>.oid</TT
></TD
><TD
>Type modifier output function, or 0 to use the standard format</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>typanalyze</TT
></TD
><TD
><TT
CLASS="TYPE"
>regproc</TT
></TD
><TD
><TT
CLASS="LITERAL"
><A
HREF="catalog-pg-proc.html"
><TT
CLASS="STRUCTNAME"
>pg_proc</TT
></A
>.oid</TT
></TD
><TD
>Custom ANALYZE function, or 0 to use the standard function</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>typalign</TT
></TD
><TD
><TT
CLASS="TYPE"
>char</TT
></TD
><TD
> </TD
><TD
><P
> <TT
CLASS="STRUCTFIELD"
>typalign</TT
> 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
<SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
>.
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.
</P
><P
> Possible values are:
<P
></P
></P><UL
><LI
><P
><TT
CLASS="LITERAL"
>c</TT
> = <TT
CLASS="TYPE"
>char</TT
> alignment, i.e., no alignment needed.</P
></LI
><LI
><P
><TT
CLASS="LITERAL"
>s</TT
> = <TT
CLASS="TYPE"
>short</TT
> alignment (2 bytes on most machines).</P
></LI
><LI
><P
><TT
CLASS="LITERAL"
>i</TT
> = <TT
CLASS="TYPE"
>int</TT
> alignment (4 bytes on most machines).</P
></LI
><LI
><P
><TT
CLASS="LITERAL"
>d</TT
> = <TT
CLASS="TYPE"
>double</TT
> alignment (8 bytes on many machines, but by no means all).</P
></LI
></UL
><P>
</P
><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
><P
><B
>Note: </B
> For types used in system tables, it is critical that the size
and alignment defined in <TT
CLASS="STRUCTNAME"
>pg_type</TT
>
agree with the way that the compiler will lay out the column in
a structure representing a table row.
</P
></BLOCKQUOTE
></DIV
></TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>typstorage</TT
></TD
><TD
><TT
CLASS="TYPE"
>char</TT
></TD
><TD
> </TD
><TD
><P
> <TT
CLASS="STRUCTFIELD"
>typstorage</TT
> tells for varlena
types (those with <TT
CLASS="STRUCTFIELD"
>typlen</TT
> = -1) if
the type is prepared for toasting and what the default strategy
for attributes of this type should be.
Possible values are
<P
></P
></P><UL
><LI
><P
><TT
CLASS="LITERAL"
>p</TT
>: Value must always be stored plain.</P
></LI
><LI
><P
> <TT
CLASS="LITERAL"
>e</TT
>: Value can be stored in a <SPAN
CLASS="QUOTE"
>"secondary"</SPAN
>
relation (if relation has one, see
<TT
CLASS="LITERAL"
>pg_class.reltoastrelid</TT
>).
</P
></LI
><LI
><P
><TT
CLASS="LITERAL"
>m</TT
>: Value can be stored compressed inline.</P
></LI
><LI
><P
><TT
CLASS="LITERAL"
>x</TT
>: Value can be stored compressed inline or stored in <SPAN
CLASS="QUOTE"
>"secondary"</SPAN
> storage.</P
></LI
></UL
><P>
Note that <TT
CLASS="LITERAL"
>m</TT
> columns can also be moved out to secondary
storage, but only as a last resort (<TT
CLASS="LITERAL"
>e</TT
> and <TT
CLASS="LITERAL"
>x</TT
> columns are
moved first).
</P
></TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>typnotnull</TT
></TD
><TD
><TT
CLASS="TYPE"
>bool</TT
></TD
><TD
> </TD
><TD
><P
> <TT
CLASS="STRUCTFIELD"
>typnotnull</TT
> represents a not-null
constraint on a type. Used for domains only
</P
></TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>typbasetype</TT
></TD
><TD
><TT
CLASS="TYPE"
>oid</TT
></TD
><TD
><TT
CLASS="LITERAL"
><A
HREF="catalog-pg-type.html"
><TT
CLASS="STRUCTNAME"
>pg_type</TT
></A
>.oid</TT
></TD
><TD
><P
> If this is a domain (see <TT
CLASS="STRUCTFIELD"
>typtype</TT
>), then
<TT
CLASS="STRUCTFIELD"
>typbasetype</TT
> identifies the type that this
one is based on. Zero if this type is not a domain
</P
></TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>typtypmod</TT
></TD
><TD
><TT
CLASS="TYPE"
>int4</TT
></TD
><TD
> </TD
><TD
><P
> Domains use <TT
CLASS="STRUCTFIELD"
>typtypmod</TT
> to record the <TT
CLASS="LITERAL"
>typmod</TT
>
to be applied to their base type (-1 if base type does not use a
<TT
CLASS="LITERAL"
>typmod</TT
>). -1 if this type is not a domain
</P
></TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>typndims</TT
></TD
><TD
><TT
CLASS="TYPE"
>int4</TT
></TD
><TD
> </TD
><TD
><P
> <TT
CLASS="STRUCTFIELD"
>typndims</TT
> is the number of array dimensions
for a domain that is an array (that is, <TT
CLASS="STRUCTFIELD"
>typbasetype</TT
> is
an array type; the domain's <TT
CLASS="STRUCTFIELD"
>typelem</TT
> will match the base
type's <TT
CLASS="STRUCTFIELD"
>typelem</TT
>).
Zero for types other than domains over array types
</P
></TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>typdefaultbin</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
> </TD
><TD
><P
> If <TT
CLASS="STRUCTFIELD"
>typdefaultbin</TT
> is not null, it is the <CODE
CLASS="FUNCTION"
>nodeToString()</CODE
>
representation of a default expression for the type. This is
only used for domains
</P
></TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>typdefault</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
> </TD
><TD
><P
> <TT
CLASS="STRUCTFIELD"
>typdefault</TT
> is null if the type has no associated
default value. If <TT
CLASS="STRUCTFIELD"
>typdefaultbin</TT
> is not null,
<TT
CLASS="STRUCTFIELD"
>typdefault</TT
> must contain a human-readable version of the
default expression represented by <TT
CLASS="STRUCTFIELD"
>typdefaultbin</TT
>. If
<TT
CLASS="STRUCTFIELD"
>typdefaultbin</TT
> is null and <TT
CLASS="STRUCTFIELD"
>typdefault</TT
> is
not, then <TT
CLASS="STRUCTFIELD"
>typdefault</TT
> is the external representation of
the type's default value, which might be fed to the type's input
converter to produce a constant
</P
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distrib
>
Mandriva
>
2008.1
>
x86_64
>
media
>
main-testing
>
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>
bab02a23fa9f3df8d66a9a3231b50245
>
files
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