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Allow special '$libdir' macro to show up in object file path in CREATE

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FUNCTION command.  Guard against trying to load a directory.  Update
documentation some.
This commit is contained in:
Peter Eisentraut
2001-05-19 09:01:10 +00:00
parent a008109d05
commit cb8b40e6d5
7 changed files with 394 additions and 529 deletions
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193
doc/src/sgml/ref/load.sgml
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@@ -1,183 +1,54 @@
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/ref/load.sgml,v 1.7 1999/07/22 15:09:12 thomas Exp $
Postgres documentation
$Header: /cvsroot/pgsql/doc/src/sgml/ref/load.sgml,v 1.8 2001/05/19 09:01:10 petere Exp $
-->
<refentry id="SQL-LOAD">
<refmeta>
<refentrytitle id="SQL-LOAD-TITLE">
LOAD
</refentrytitle>
<refentrytitle>LOAD</refentrytitle>
<refmiscinfo>SQL - Language Statements</refmiscinfo>
</refmeta>
<refnamediv>
<refname>
LOAD
</refname>
<refpurpose>
Dynamically loads an object file
</refpurpose>
<refname>LOAD</refname>
<refpurpose>Loads a shared object file</refpurpose>
</refnamediv>
<refsynopsisdiv>
<refsynopsisdivinfo>
<date>1999-07-20</date>
</refsynopsisdivinfo>
<synopsis>
<synopsis>
LOAD '<replaceable class="PARAMETER">filename</replaceable>'
</synopsis>
<refsect2 id="R2-SQL-LOAD-1">
<refsect2info>
<date>1998-09-01</date>
</refsect2info>
<title>
Inputs
</title>
<para>
<variablelist>
<varlistentry>
<term><replaceable class="PARAMETER">filename</replaceable></term>
<listitem>
<para>
Object file for dynamic loading.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect2>
<refsect2 id="R2-SQL-LOAD-2">
<refsect2info>
<date>1998-09-24</date>
</refsect2info>
<title>
Outputs
</title>
<para>
<variablelist>
<varlistentry>
<term><computeroutput>
LOAD
</computeroutput></term>
<listitem>
<para>
Message returned on successful completion.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><computeroutput>
ERROR: LOAD: could not open file '<replaceable class="PARAMETER">filename</replaceable>'
</computeroutput></term>
<listitem>
<para>
Message returned if the specified file is not found. The file must be visible
<emphasis>to the <productname>Postgres</productname> backend</emphasis>,
with the appropriate full path name specified, to avoid this message.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect2>
</synopsis>
</refsynopsisdiv>
<refsect1 id="R1-SQL-LOAD-1">
<refsect1info>
<date>1998-09-24</date>
</refsect1info>
<title>
Description
</title>
<refsect1 id="sql-load-description">
<title>Description</title>
<para>
Loads an object (or ".o") file into the
<productname>Postgres</productname> backend address space. Once a
file is loaded, all functions in that file can be accessed. This
function is used in support of user-defined types and functions.
</para>
<para>
If a file is not loaded using
<command>LOAD</command>,
the file will be loaded automatically the first time the
function is called by <productname>Postgres</productname>.
<command>LOAD</command>
can also be used to reload an object file if it has been edited and
recompiled. Only objects created from C language files are supported
at this time.
</para>
<refsect2 id="R2-SQL-LOAD-3">
<refsect2info>
<date>1998-09-24</date>
</refsect2info>
<title>
Notes
</title>
<para>
Functions in loaded object files should not call functions in other
object files loaded through the
<command>LOAD</command>
command. For example, all functions in file <literal>A</literal> should
call each other, functions in the standard or math libraries, or in
Postgres itself. They should not call functions defined in a different
loaded file <literal>B</literal>.
This is because if <literal>B</literal> is reloaded, the Postgres loader is
not able to relocate the calls from the functions in
<literal>A</literal> into
the new address space of <literal>B</literal>.
If <literal>B</literal> is not reloaded, however, there will
not be a problem.
</para>
<para>
Object files must be compiled to contain position independent code.
For example,
on DECstations you must use
<application>/bin/cc</application>
with the <literal>-G 0</literal> option when compiling object files to be
loaded.
</para>
<para>
Note that if you are porting <productname>Postgres</productname>
to a new platform, <command>LOAD</command>
will have to work in order to support ADTs.
</para>
</refsect2>
</refsect1>
<refsect1 id="R1-SQL-LOAD-2">
<title>
Usage
</title>
<para>
Load the file <filename>/usr/postgres/demo/circle.o</filename>:
<programlisting>
LOAD '/usr/postgres/demo/circle.o'
</programlisting>
Loads a shared object file into the PostgreSQL backend's address
space. If the file had been loaded previously, it is first
unloaded. This command is primarily useful to unload and reload a
shared object file if it has been changed. To make use of the
shared object, a function needs to be declared using the <xref
linkend="sql-createfunction"> command.
</para>
</refsect1>
<refsect1 id="R1-SQL-LOAD-3">
<title>
Compatibility
</title>
<refsect1 id="sql-load-compat">
<title>Compatibility</title>
<refsect2 id="R2-SQL-LOAD-4">
<refsect2info>
<date>1998-09-24</date>
</refsect2info>
<title>
SQL92
</title>
<para>
There is no <command>LOAD</command> in <acronym>SQL92</acronym>.
</para>
</refsect2>
<para>
<command>LOAD</command> is a <application>PostgreSQL</application>
extension.
</para>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<xref linkend="sql-createfunction">,
<citetitle>PostgreSQL Programmer's Guide</citetitle>
</para>
</refsect1>
</refentry>