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$PostgreSQL: pgsql/doc/src/sgml/ref/create_type.sgml,v 1.74 2008/05/27 18:05:13 tgl Exp $

PostgreSQL documentation

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attached to a type declaration, such as <literal>char(5)</> or

<literal>numeric(30,2)</>. <productname>PostgreSQL</productname> allows

user-defined types to take one or more simple constants or identifiers as

modifiers; however, this information must be capable of being packed into a

modifiers. However, this information must be capable of being packed into a

single non-negative integer value for storage in the system catalogs. The

<replaceable class="parameter">type_modifier_input_function</replaceable>

is passed the declared modifier(s) in the form of a <type>cstring</>

function might return <literal>(30,2)</>.

It is allowed to omit the

<replaceable class="parameter">type_modifier_output_function</replaceable>,

in which case the default display format is just the stored typmodvalue

enclosed in parentheses.

in which case the default display format is just the stored typmodinteger

valueenclosed in parentheses.

</para>

<para>

<term><replaceable class="parameter">type_modifier_input_function</replaceable></term>

<listitem>

<para>

The name of a function that convertsnumeric modifier(s) for the type

The name of a function that convertsan array of modifier(s) for the type

into internal form.

</para>

</listitem>