mirror of
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Allow special '$libdir' macro to show up in object file path in CREATE
FUNCTION command. Guard against trying to load a directory. Update documentation some.
This commit is contained in:
Peter Eisentraut
@ -1,187 +1,151 @@
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<!--
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$Header: /cvsroot/pgsql/doc/src/sgml/ref/create_function.sgml,v 1.22 2001/04/28 13:59:07 momjian Exp $
|
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Postgres documentation
|
||||
$Header: /cvsroot/pgsql/doc/src/sgml/ref/create_function.sgml,v 1.23 2001/05/19 09:01:10 petere Exp $
|
||||
-->
|
||||
|
||||
<refentry id="SQL-CREATEFUNCTION">
|
||||
<refmeta>
|
||||
<refentrytitle id="sql-createfunction-title">
|
||||
CREATE FUNCTION
|
||||
</refentrytitle>
|
||||
<refentrytitle>CREATE FUNCTION</refentrytitle>
|
||||
<refmiscinfo>SQL - Language Statements</refmiscinfo>
|
||||
</refmeta>
|
||||
|
||||
<refnamediv>
|
||||
<refname>
|
||||
CREATE FUNCTION
|
||||
</refname>
|
||||
<refpurpose>
|
||||
Defines a new function
|
||||
</refpurpose>
|
||||
<refname>CREATE FUNCTION</refname>
|
||||
<refpurpose>Defines a new function</refpurpose>
|
||||
</refnamediv>
|
||||
|
||||
<refsynopsisdiv>
|
||||
<refsynopsisdivinfo>
|
||||
<date>2000-03-25</date>
|
||||
</refsynopsisdivinfo>
|
||||
<synopsis>
|
||||
CREATE FUNCTION <replaceable class="parameter">name</replaceable> ( [ <replaceable class="parameter">ftype</replaceable> [, ...] ] )
|
||||
RETURNS <replaceable class="parameter">rtype</replaceable>
|
||||
AS <replaceable class="parameter">definition</replaceable>
|
||||
<synopsis>
|
||||
CREATE FUNCTION <replaceable class="parameter">name</replaceable> ( [ <replaceable class="parameter">argtype</replaceable> [, ...] ] )
|
||||
RETURNS <replaceable class="parameter">rettype</replaceable>
|
||||
AS '<replaceable class="parameter">definition</replaceable>'
|
||||
LANGUAGE '<replaceable class="parameter">langname</replaceable>'
|
||||
[ WITH ( <replaceable class="parameter">attribute</replaceable> [, ...] ) ]
|
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CREATE FUNCTION <replaceable class="parameter">name</replaceable> ( [ <replaceable class="parameter">ftype</replaceable> [, ...] ] )
|
||||
RETURNS <replaceable class="parameter">rtype</replaceable>
|
||||
AS <replaceable class="parameter">obj_file</replaceable> , <replaceable class="parameter">link_symbol</replaceable>
|
||||
LANGUAGE 'langname'
|
||||
CREATE FUNCTION <replaceable class="parameter">name</replaceable> ( [ <replaceable class="parameter">argtype</replaceable> [, ...] ] )
|
||||
RETURNS <replaceable class="parameter">rettype</replaceable>
|
||||
AS '<replaceable class="parameter">obj_file</replaceable>', '<replaceable class="parameter">link_symbol</replaceable>'
|
||||
LANGUAGE '<replaceable class="parameter">langname</replaceable>'
|
||||
[ WITH ( <replaceable class="parameter">attribute</replaceable> [, ...] ) ]
|
||||
</synopsis>
|
||||
|
||||
<refsect2 id="R2-SQL-CREATEFUNCTION-1">
|
||||
<refsect2info>
|
||||
<date>2000-03-25</date>
|
||||
</refsect2info>
|
||||
<title>
|
||||
Inputs
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||||
</title>
|
||||
<para>
|
||||
|
||||
<variablelist>
|
||||
<varlistentry>
|
||||
<term><replaceable class="parameter">name</replaceable></term>
|
||||
<listitem>
|
||||
<para>
|
||||
The name of a function to create.
|
||||
</para>
|
||||
</listitem>
|
||||
</varlistentry>
|
||||
<varlistentry>
|
||||
<term><replaceable class="parameter">ftype</replaceable></term>
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||||
<listitem>
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||||
<para>
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The data type(s) of the function's arguments, if any.
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The input types may be base or complex types, or
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<firstterm>opaque</firstterm>.
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<literal>Opaque</literal> indicates that the function
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accepts arguments of a non-SQL type such as <type>char *</type>.
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</para>
|
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</listitem>
|
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</varlistentry>
|
||||
<varlistentry>
|
||||
<term><replaceable class="parameter">rtype</replaceable></term>
|
||||
<listitem>
|
||||
<para>
|
||||
The return data type.
|
||||
The output type may be specified as a base type, complex type,
|
||||
<option>setof type</option>,
|
||||
or <option>opaque</option>.
|
||||
The <option>setof</option>
|
||||
modifier indicates that the function will return a set of items,
|
||||
rather than a single item.
|
||||
</para>
|
||||
</listitem>
|
||||
</varlistentry>
|
||||
<varlistentry>
|
||||
<term><replaceable class="parameter">attribute</replaceable></term>
|
||||
<listitem>
|
||||
<para>
|
||||
An optional piece of information about the function, used for
|
||||
optimization. See below for details.
|
||||
</para>
|
||||
</listitem>
|
||||
</varlistentry>
|
||||
<varlistentry>
|
||||
<term><replaceable class="parameter">definition</replaceable></term>
|
||||
<listitem>
|
||||
<para>
|
||||
A string defining the function; the meaning depends on the language.
|
||||
It may be an internal function name, the path to an object file,
|
||||
an SQL query, or text in a procedural language.
|
||||
</para>
|
||||
</listitem>
|
||||
</varlistentry>
|
||||
<varlistentry>
|
||||
<term><replaceable class="parameter">obj_file</replaceable> , <replaceable class="parameter">link_symbol</replaceable></term>
|
||||
<listitem>
|
||||
<para>
|
||||
This form of the <command>AS</command> clause is used for
|
||||
dynamically linked, C language functions when the function name in
|
||||
the C language source code is not the same as the name of the SQL
|
||||
function. The string <replaceable
|
||||
class="parameter">obj_file</replaceable> is the name of the file
|
||||
containing the dynamically loadable object, and <replaceable
|
||||
class="parameter">link_symbol</replaceable> is the object's link
|
||||
symbol, that is the name of the function in the C
|
||||
language source code.
|
||||
</para>
|
||||
</listitem>
|
||||
</varlistentry>
|
||||
<varlistentry>
|
||||
<term><replaceable class="parameter">langname</replaceable></term>
|
||||
<listitem>
|
||||
<para>
|
||||
May be '<literal>sql</literal>',
|
||||
'<literal>C</literal>', '<literal>internal</literal>',
|
||||
or '<replaceable class="parameter">plname</replaceable>',
|
||||
where '<replaceable class="parameter">plname</replaceable>'
|
||||
is the name of a created procedural language. See
|
||||
<xref linkend="sql-createlanguage" endterm="sql-createlanguage-title">
|
||||
for details.
|
||||
</para>
|
||||
</listitem>
|
||||
</varlistentry>
|
||||
</variablelist>
|
||||
</para>
|
||||
</refsect2>
|
||||
|
||||
<refsect2 id="R2-SQL-CREATEFUNCTION-2">
|
||||
<refsect2info>
|
||||
<date>2000-03-25</date>
|
||||
</refsect2info>
|
||||
<title>
|
||||
Outputs
|
||||
</title>
|
||||
<para>
|
||||
|
||||
<variablelist>
|
||||
<varlistentry>
|
||||
<term><computeroutput>
|
||||
CREATE
|
||||
</computeroutput></term>
|
||||
<listitem>
|
||||
<para>
|
||||
This is returned if the command completes successfully.
|
||||
</para>
|
||||
</listitem>
|
||||
</varlistentry>
|
||||
</variablelist>
|
||||
</para>
|
||||
</refsect2>
|
||||
</synopsis>
|
||||
</refsynopsisdiv>
|
||||
|
||||
<refsect1 id="sql-createfunction-description">
|
||||
<title>Description</title>
|
||||
|
||||
<refsect1 id="R1-SQL-CREATEFUNCTION-1">
|
||||
<refsect1info>
|
||||
<date>2000-03-25</date>
|
||||
</refsect1info>
|
||||
<title>
|
||||
Description
|
||||
</title>
|
||||
<para>
|
||||
<command>CREATE FUNCTION</command> allows a
|
||||
<productname>Postgres</productname> user
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||||
to register a function
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||||
with the database. Subsequently, this user is considered the
|
||||
owner of the function.
|
||||
<command>CREATE FUNCTION</command> defines a new function.
|
||||
|
||||
<variablelist>
|
||||
<title>Parameters</title>
|
||||
|
||||
<varlistentry>
|
||||
<term><replaceable class="parameter">name</replaceable></term>
|
||||
|
||||
<listitem>
|
||||
<para>
|
||||
The name of a function to create. The name need not be unique,
|
||||
because functions may be overloaded, but functions with the
|
||||
same name must have different argument types.
|
||||
</para>
|
||||
</listitem>
|
||||
</varlistentry>
|
||||
|
||||
<varlistentry>
|
||||
<term><replaceable class="parameter">argtype</replaceable></term>
|
||||
|
||||
<listitem>
|
||||
<para>
|
||||
The data type(s) of the function's arguments, if any. The
|
||||
input types may be base or complex types, or
|
||||
<literal>opaque</literal>. <literal>Opaque</literal> indicates
|
||||
that the function accepts arguments of a non-SQL type such as
|
||||
<type>char *</type>.
|
||||
</para>
|
||||
</listitem>
|
||||
</varlistentry>
|
||||
|
||||
<varlistentry>
|
||||
<term><replaceable class="parameter">rettype</replaceable></term>
|
||||
|
||||
<listitem>
|
||||
<para>
|
||||
The return data type. The output type may be specified as a
|
||||
base type, complex type, <literal>setof</literal> type, or
|
||||
<literal>opaque</literal>. The <literal>setof</literal>
|
||||
modifier indicates that the function will return a set of
|
||||
items, rather than a single item. Functions with a declared
|
||||
return type of <literal>opaque</literal> do not return a value.
|
||||
These cannot be called directly; trigger functions make use of
|
||||
this feature.
|
||||
</para>
|
||||
</listitem>
|
||||
</varlistentry>
|
||||
|
||||
<varlistentry>
|
||||
<term><replaceable class="parameter">definition</replaceable></term>
|
||||
|
||||
<listitem>
|
||||
<para>
|
||||
A string defining the function; the meaning depends on the
|
||||
language. It may be an internal function name, the path to an
|
||||
object file, an SQL query, or text in a procedural language.
|
||||
</para>
|
||||
</listitem>
|
||||
</varlistentry>
|
||||
|
||||
<varlistentry>
|
||||
<term><replaceable class="parameter">obj_file</replaceable>, <replaceable class="parameter">link_symbol</replaceable></term>
|
||||
|
||||
<listitem>
|
||||
<para>
|
||||
This form of the <literal>AS</literal> clause is used for
|
||||
dynamically linked C language functions when the function name
|
||||
in the C language source code is not the same as the name of
|
||||
the SQL function. The string <replaceable
|
||||
class="parameter">obj_file</replaceable> is the name of the
|
||||
file containing the dynamically loadable object, and
|
||||
<replaceable class="parameter">link_symbol</replaceable> is the
|
||||
object's link symbol, that is, the name of the function in the C
|
||||
language source code.
|
||||
</para>
|
||||
</listitem>
|
||||
</varlistentry>
|
||||
|
||||
<varlistentry>
|
||||
<term><replaceable class="parameter">langname</replaceable></term>
|
||||
|
||||
<listitem>
|
||||
<para>
|
||||
May be '<literal>sql</literal>', '<literal>C</literal>',
|
||||
'<literal>internal</literal>', or '<replaceable
|
||||
class="parameter">plname</replaceable>', where '<replaceable
|
||||
class="parameter">plname</replaceable>' is the name of a
|
||||
created procedural language. See
|
||||
<xref linkend="sql-createlanguage">
|
||||
for details.
|
||||
</para>
|
||||
</listitem>
|
||||
</varlistentry>
|
||||
|
||||
<varlistentry>
|
||||
<term><replaceable class="parameter">attribute</replaceable></term>
|
||||
|
||||
<listitem>
|
||||
<para>
|
||||
An optional piece of information about the function, used for
|
||||
optimization. See below for details.
|
||||
</para>
|
||||
</listitem>
|
||||
</varlistentry>
|
||||
|
||||
</variablelist>
|
||||
</para>
|
||||
|
||||
<refsect2 id="R2-SQL-CREATEFUNCTION-3">
|
||||
<refsect2info>
|
||||
<date>2000-08-24</date>
|
||||
</refsect2info>
|
||||
<title>
|
||||
Function Attributes
|
||||
</title>
|
||||
<para>
|
||||
The user that creates the function becomes the owner of the function.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
The following items may appear in the WITH clause:
|
||||
<para>
|
||||
The following attributes may appear in the WITH clause:
|
||||
|
||||
<variablelist>
|
||||
<varlistentry>
|
||||
@ -214,17 +178,12 @@ CREATE
|
||||
</listitem>
|
||||
</varlistentry>
|
||||
</variablelist>
|
||||
</para>
|
||||
</para>
|
||||
|
||||
</refsect2>
|
||||
</refsect1>
|
||||
|
||||
<refsect2 id="R2-SQL-CREATEFUNCTION-4">
|
||||
<refsect2info>
|
||||
<date>2000-03-25</date>
|
||||
</refsect2info>
|
||||
<title>
|
||||
Notes
|
||||
</title>
|
||||
<refsect1 id="sql-createfunction-notes">
|
||||
<title>Notes</title>
|
||||
|
||||
<para>
|
||||
Refer to the chapter in the
|
||||
@ -240,7 +199,7 @@ CREATE
|
||||
</para>
|
||||
|
||||
<para>
|
||||
The full <acronym>SQL92</acronym> type syntax is allowed for
|
||||
The full <acronym>SQL</acronym> type syntax is allowed for
|
||||
input arguments and return value. However, some details of the
|
||||
type specification (e.g., the precision field for
|
||||
<type>numeric</type> types) are the responsibility of the
|
||||
@ -250,7 +209,7 @@ CREATE
|
||||
</para>
|
||||
|
||||
<para>
|
||||
<productname>Postgres</productname> allows function "overloading";
|
||||
<productname>Postgres</productname> allows function <firstterm>overloading</firstterm>;
|
||||
that is, the same name can be used for several different functions
|
||||
so long as they have distinct argument types. This facility must
|
||||
be used with caution for internal and C-language functions, however.
|
||||
@ -275,38 +234,45 @@ CREATE
|
||||
C-language implementation of each overloaded SQL function.
|
||||
</para>
|
||||
|
||||
</refsect2>
|
||||
<para>
|
||||
When repeated <command>CREATE FUNCTION</command> calls refer to
|
||||
the same object file, the file is only loaded once. To unload and
|
||||
reload the file (perhaps during development), use the <xref
|
||||
linkend="sql-load"> command.
|
||||
</para>
|
||||
|
||||
</refsect1>
|
||||
|
||||
|
||||
<refsect1 id="R1-SQL-CREATEFUNCTION-2">
|
||||
<title>
|
||||
Usage
|
||||
</title>
|
||||
<refsect1 id="sql-createfunction-examples">
|
||||
<title>Examples</title>
|
||||
|
||||
<para>
|
||||
To create a simple SQL function:
|
||||
|
||||
<programlisting>
|
||||
CREATE FUNCTION one() RETURNS int4
|
||||
AS 'SELECT 1 AS RESULT'
|
||||
<programlisting>
|
||||
CREATE FUNCTION one() RETURNS integer
|
||||
AS 'SELECT 1 AS RESULT;'
|
||||
LANGUAGE 'sql';
|
||||
SELECT one() AS answer;
|
||||
|
||||
<computeroutput>
|
||||
SELECT one() AS answer;
|
||||
<computeroutput>
|
||||
answer
|
||||
--------
|
||||
1
|
||||
</computeroutput>
|
||||
</programlisting>
|
||||
</computeroutput>
|
||||
</programlisting>
|
||||
</para>
|
||||
|
||||
<para>
|
||||
This example creates a C function by calling a routine from a user-created
|
||||
shared library. This particular routine calculates a check
|
||||
digit and returns TRUE if the check digit in the function parameters
|
||||
is correct. It is intended for use in a CHECK contraint.
|
||||
</para>
|
||||
<programlisting>
|
||||
CREATE FUNCTION ean_checkdigit(bpchar, bpchar) RETURNS boolean
|
||||
The next example creates a C function by calling a routine from a
|
||||
user-created shared library. This particular routine calculates a
|
||||
check digit and returns TRUE if the check digit in the function
|
||||
parameters is correct. It is intended for use in a CHECK
|
||||
constraint.
|
||||
|
||||
<programlisting>
|
||||
CREATE FUNCTION ean_checkdigit(char, char) RETURNS boolean
|
||||
AS '/usr1/proj/bray/sql/funcs.so' LANGUAGE 'c';
|
||||
|
||||
CREATE TABLE product (
|
||||
@ -316,28 +282,28 @@ CREATE TABLE product (
|
||||
eancode char(6) CHECK (eancode ~ '[0-9]{6}'),
|
||||
CONSTRAINT ean CHECK (ean_checkdigit(eanprefix, eancode))
|
||||
);
|
||||
</programlisting>
|
||||
|
||||
</programlisting>
|
||||
</para>
|
||||
|
||||
<para>
|
||||
This example creates a function that does type conversion between the
|
||||
user-defined type complex, and the internal type point. The
|
||||
function is implemented by a dynamically loaded object that was
|
||||
compiled from C source. For <productname>Postgres</productname> to
|
||||
find a type conversion function automatically, the sql function has
|
||||
compiled from C source. For <productname>PostgreSQL</productname> to
|
||||
find a type conversion function automatically, the SQL function has
|
||||
to have the same name as the return type, and so overloading is
|
||||
unavoidable. The function name is overloaded by using the second
|
||||
form of the <command>AS</command> clause in the SQL definition:
|
||||
</para>
|
||||
<programlisting>
|
||||
|
||||
<programlisting>
|
||||
CREATE FUNCTION point(complex) RETURNS point
|
||||
AS '/home/bernie/pgsql/lib/complex.so', 'complex_to_point'
|
||||
LANGUAGE 'c';
|
||||
</programlisting>
|
||||
<para>
|
||||
The C declaration of the function is:
|
||||
</para>
|
||||
<programlisting>
|
||||
</programlisting>
|
||||
|
||||
The C declaration of the function could be:
|
||||
|
||||
<programlisting>
|
||||
Point * complex_to_point (Complex *z)
|
||||
{
|
||||
Point *p;
|
||||
@ -348,58 +314,33 @@ Point * complex_to_point (Complex *z)
|
||||
|
||||
return p;
|
||||
}
|
||||
</programlisting>
|
||||
|
||||
|
||||
</programlisting>
|
||||
</para>
|
||||
</refsect1>
|
||||
|
||||
|
||||
<refsect1 id="R1-SQL-CREATEFUNCTION-4">
|
||||
<title>
|
||||
Compatibility
|
||||
</title>
|
||||
<refsect1 id="sql-createfunction-compat">
|
||||
<title>Compatibility</title>
|
||||
|
||||
<refsect2 id="R2-SQL-CREATEFUNCTION-5">
|
||||
<refsect2info>
|
||||
<date>2000-03-25</date>
|
||||
</refsect2info>
|
||||
<title>
|
||||
SQL92
|
||||
</title>
|
||||
|
||||
<para>
|
||||
<command>CREATE FUNCTION</command> is
|
||||
a <productname>Postgres</productname> language extension.
|
||||
</para>
|
||||
</refsect2>
|
||||
|
||||
<refsect2 id="R2-SQL-CREATEFUNCTION-6">
|
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<refsect2info>
|
||||
<date>2000-03-25</date>
|
||||
</refsect2info>
|
||||
<title>
|
||||
SQL/PSM
|
||||
</title>
|
||||
<para>
|
||||
|
||||
<note>
|
||||
<para>
|
||||
PSM stands for Persistent Stored Modules. It is a procedural
|
||||
language. SQL/PSM is a standard to enable function extensibility.
|
||||
</para>
|
||||
</note>
|
||||
|
||||
SQL/PSM <command>CREATE FUNCTION</command> has the following syntax:
|
||||
<synopsis>
|
||||
CREATE FUNCTION <replaceable class="parameter">name</replaceable>
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||||
( [ [ IN | OUT | INOUT ] <replaceable class="parameter">type</replaceable> [, ...] ] )
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||||
RETURNS <replaceable class="parameter">rtype</replaceable>
|
||||
LANGUAGE '<replaceable class="parameter">langname</replaceable>'
|
||||
ESPECIFIC <replaceable class="parameter">routine</replaceable>
|
||||
<replaceable class="parameter">SQL-statement</replaceable>
|
||||
</synopsis>
|
||||
</para>
|
||||
</refsect2>
|
||||
<para>
|
||||
A <command>CREATE FUNCTION</command> command is defined in SQL99.
|
||||
The <application>PostgreSQL</application> version is similar but
|
||||
not compatible. The attributes are not portable, neither are the
|
||||
different available languages.
|
||||
</para>
|
||||
</refsect1>
|
||||
|
||||
|
||||
<refsect1 id="sql-createfunction-seealso">
|
||||
<title>See Also</title>
|
||||
|
||||
<para>
|
||||
<xref linkend="sql-dropfunction">,
|
||||
<xref linkend="sql-load">,
|
||||
<citetitle>PostgreSQL Programmer's Guide</citetitle>
|
||||
</para>
|
||||
</refsect1>
|
||||
|
||||
</refentry>
|
||||
|
||||
<!-- Keep this comment at the end of the file
|
||||
|
||||
Reference in New Issue
Block a user