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Thomas G. Lockhart
1998-09-16 14:43:12 +00:00
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doc/src/sgml/ref/create_language.sgml
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@ -15,29 +15,22 @@
<REFSYNOPSISDIV>
<REFSYNOPSISDIVINFO>
<DATE>1998-04-15</DATE>
<DATE>1998-09-09</DATE>
</REFSYNOPSISDIVINFO>
<SYNOPSIS>
CREATE [TRUSTED] PROCEDURAL LANGUAGE '<replaceable class="parameter">langname</replaceable>'
HANDLER <replaceable class="parameter">call_handler</replaceable>
LANCOMPILER '<replaceable class="parameter">comment</replaceable>'
CREATE [ TRUSTED ] PROCEDURAL LANGUAGE '<replaceable class="parameter">langname</replaceable>'
HANDLER <replaceable class="parameter">call_handler</replaceable>
LANCOMPILER '<replaceable class="parameter">comment</replaceable>'
</SYNOPSIS>
<REFSECT2 ID="R2-SQL-CREATELANGUAGE-1">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
<DATE>1998-09-09</DATE>
</REFSECT2INFO>
<TITLE>
Inputs
</TITLE>
<PARA>
</PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
</TERM>
<LISTITEM>
<PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
@ -99,14 +92,12 @@
</LISTITEM>
</VARLISTENTRY>
</variablelist>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
</REFSECT2>
<REFSECT2 ID="R2-SQL-CREATELANGUAGE-2">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
<DATE>1998-09-09</DATE>
</REFSECT2INFO>
<TITLE>
Outputs
@ -116,6 +107,7 @@
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<replaceable>status</replaceable>
</TERM>
<LISTITEM>
<PARA>
@ -152,22 +144,25 @@
<REFSECT1 ID="R1-SQL-CREATELANGUAGE-1">
<REFSECT1INFO>
<DATE>1998-04-15</DATE>
<DATE>1998-09-09</DATE>
</REFSECT1INFO>
<TITLE>
Description
</TITLE>
<PARA>
Using <command>CREATE LANGUAGE</command>, a PostgreSQL user can register
a new language with PostgreSQL. Subsequently, functions and
Using <command>CREATE LANGUAGE</command>, a
<productname>Postgres</productname> user can register
a new language with <productname>Postgres</productname>.
Subsequently, functions and
trigger procedures can be defined in this new language.
The user must have the PostgreSQL superuser privilege to
The user must have the <productname>Postgres</productname>
superuser privilege to
register a new language.
</PARA>
<REFSECT2 ID="R2-SQL-CREATELANGUAGE-3">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
<DATE>1998-09-09</DATE>
</REFSECT2INFO>
<TITLE>
Writing PL handlers
@ -175,9 +170,9 @@
<PARA>
The call handler for a procedural language must be written
in a compiler language such as 'C' and registered with
PostgreSQL as a function taking no arguments and returning
opaque type.
<comment>What does `opaque type' mean?</comment>
<productname>Postgres</productname> as a function taking
no arguments and returning the
<type>opaque</type> type, a placeholder for unspecified or undefined types..
This prevents the call handler from being
called directly as a function from queries.
</para>
@ -214,11 +209,11 @@
It's up to the call handler to fetch the
<filename>pg_proc</filename> entry and
to analyze the argument and return types of the called
procedure. The <function>AS</function> clause from the
procedure. The AS clause from the
<command>CREATE FUNCTION</command> of
the procedure will be found in the <literal>prosrc</literal>
attribute of the
<filename>pg_proc</filename> entry. This may be the
<filename>pg_proc</filename> table entry. This may be the
source text in the procedural
language itself (like for PL/Tcl), a pathname to a
file or anything else that tells the call handler what to
@ -227,43 +222,40 @@
<REFSECT2 ID="R2-SQL-CREATELANGUAGE-4">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
<DATE>1998-09-09</DATE>
</REFSECT2INFO>
<TITLE>
Notes
</TITLE>
<PARA>
Use <citerefentry>
<refentrytitle>CREATE FUNCTION</refentrytitle>
</citerefentry>
Use <command>CREATE FUNCTION</command>
to create a function.
</para>
<para>
Use <citerefentry>
<refentrytitle>DROP LANGUAGE</refentrytitle>
</citerefentry> to drop procedural languages.
Use <command>DROP LANGUAGE</command> to drop procedural languages.
</para>
<para>
Refer to the table <filename>pg_language</filename>
for further information:
<programlisting>
<computeroutput>
Table = pg_language
+--------------------------+--------------------------+-------+
| Field | Type | Length|
+--------------------------+--------------------------+-------+
| lanname | name | 32 |
| lancompiler | text | var |
+--------------------------+--------------------------+-------+
<programlisting>
<computeroutput>
Table = pg_language
+--------------------------+--------------------------+-------+
| Field | Type | Length|
+--------------------------+--------------------------+-------+
| lanname | name | 32 |
| lancompiler | text | var |
+--------------------------+--------------------------+-------+
lanname |lancompiler
--------+--------------
internal|n/a
lisp |/usr/ucb/liszt
C |/bin/cc
sql |postgres
</computeroutput>
</programlisting>
lanname |lancompiler
--------+--------------
internal|n/a
lisp |/usr/ucb/liszt
C |/bin/cc
sql |postgres
</computeroutput>
</programlisting>
</para>
</refsect2>
</refsect1>
@ -274,11 +266,9 @@
</TITLE>
<PARA>
Since the call handler for a procedural language must be
registered with PostgreSQL in the 'C' language, it inherits
all the restrictions of 'C' functions.
<comment>
What are these restrictions?
</comment>
registered with <productname>Postgres</productname> in the 'C' language,
it inherits
all the capabilities and restrictions of 'C' functions.
</para>
</refsect1>
<REFSECT1 ID="R1-SQL-CREATELANGUAGE-5">
@ -340,22 +330,21 @@
</ProgramListing>
<para>
Only a few thousand lines of code have to be added instead
of the dots to complete the PL call handler. See <citerefentry>
<refentrytitle>CREATE FUNCTION</refentrytitle>
</citerefentry> for information on how to compile
of the dots to complete the PL call handler.
See <command>CREATE FUNCTION</command> for information on how to compile
it into a loadable module
.</para>
<para>
The following commands then register the sample procedural
language.</para>
language:
<programlisting>
CREATE FUNCTION plsample_call_handler () RETURNS opaque
AS '/usr/local/pgsql/lib/plsample.so'
LANGUAGE 'C';
CREATE FUNCTION plsample_call_handler () RETURNS opaque
AS '/usr/local/pgsql/lib/plsample.so'
LANGUAGE 'C';
CREATE PROCEDURAL LANGUAGE 'plsample'
HANDLER plsample_call_handler
LANCOMPILER 'PL/Sample';
CREATE PROCEDURAL LANGUAGE 'plsample'
HANDLER plsample_call_handler
LANCOMPILER 'PL/Sample';
</programlisting>
</REFSECT1>
@ -364,18 +353,18 @@
Compatibility
</TITLE>
<PARA>
CREATE LANGUAGE is a PostgreSQL extension.
CREATE LANGUAGE is a <productname>Postgres</productname> extension.
</PARA>
<REFSECT2 ID="R2-SQL-CREATELANGUAGE-5">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
<DATE>1998-09-09</DATE>
</REFSECT2INFO>
<TITLE>
SQL92
</TITLE>
<PARA>
There is no CREATE LANGUAGE statement in SQL92.
There is no <command>CREATE LANGUAGE</command> statement in SQL92.
</PARA>
</refsect2>
</refsect1>