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Create the pg_pltemplate system catalog to hold template information

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for procedural languages.  This replaces the hard-wired table I had
originally proposed as a stopgap solution.  For the moment, the initial
contents only include languages shipped with the core distribution.
This commit is contained in:
Tom Lane
2005-09-08 20:07:42 +00:00
parent c18cabe8ab
commit 48123de717
11 changed files with 311 additions and 93 deletions
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37
doc/src/sgml/ref/create_language.sgml
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@ -1,5 +1,5 @@
<!--
$PostgreSQL: pgsql/doc/src/sgml/ref/create_language.sgml,v 1.40 2005/09/05 23:50:48 tgl Exp $
$PostgreSQL: pgsql/doc/src/sgml/ref/create_language.sgml,v 1.41 2005/09/08 20:07:41 tgl Exp $
PostgreSQL documentation
-->
@ -48,22 +48,19 @@ CREATE [ TRUSTED ] [ PROCEDURAL ] LANGUAGE <replaceable class="parameter">name</
<para>
There are two forms of the <command>CREATE LANGUAGE</command> command.
In the first form, the user merely supplies the name of the desired
In the first form, the user supplies just the name of the desired
language, and the <productname>PostgreSQL</productname> server consults
an internal table to determine the correct parameters. In
the second form, the user supplies the language parameters along with
the language name. The second form must be used to create a language
that is not present in the internal table, but this form is considered
obsolescent. (It is expected that future releases of
<productname>PostgreSQL</productname> will replace the internal table
with a system catalog that can be extended to support additional
languages.)
the <link linkend="catalog-pg-pltemplate"><structname>pg_pltemplate</structname></link>
system catalog to determine the correct parameters. In the second form,
the user supplies the language parameters along with the language name.
The second form can be used to create a language that is not defined in
<structname>pg_pltemplate</>, but this approach is considered obsolescent.
</para>
<para>
When the server finds an entry in its internal table for the given
language name, it will use the table data even if the given command
includes language parameters. This behavior simplifies loading of
When the server finds an entry in the <structname>pg_pltemplate</> catalog
for the given language name, it will use the catalog data even if the
command includes language parameters. This behavior simplifies loading of
old dump files, which are likely to contain out-of-date information
about language support functions.
</para>
@ -165,8 +162,8 @@ CREATE [ TRUSTED ] [ PROCEDURAL ] LANGUAGE <replaceable class="parameter">name</
<para>
The <literal>TRUSTED</> option and the support function name(s) are
ignored if the server has information about the specified language
name in its internal table.
ignored if the server has an entry for the specified language
name in <structname>pg_pltemplate</>.
</para>
</refsect1>
@ -207,9 +204,9 @@ CREATE [ TRUSTED ] [ PROCEDURAL ] LANGUAGE <replaceable class="parameter">name</
<para>
The call handler function and the validator function (if any)
must already exist if the server does not have information about
the language in its internal table. But when there is an entry
in the internal table, the functions need not already exist;
must already exist if the server does not have an entry for the language
in <structname>pg_pltemplate</>. But when there is an entry,
the functions need not already exist;
they will be automatically defined if not present in the database.
(This can result in <command>CREATE LANGUAGE</> failing, if the
shared library that implements the language is not available in
@ -239,8 +236,8 @@ CREATE LANGUAGE plpgsql;
</para>
<para>
For a language not known in the server's internal table, a sequence
such as this is needed:
For a language not known in the <structname>pg_pltemplate</> catalog, a
sequence such as this is needed:
<programlisting>
CREATE FUNCTION plsample_call_handler() RETURNS language_handler
AS '$libdir/plsample'