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<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>38.18. Extension Building Infrastructure</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="extend-extensions.html" title="38.17. Packaging Related Objects into an Extension" /><link rel="next" href="triggers.html" title="Chapter 39. Triggers" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">38.18. Extension Building Infrastructure</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="extend-extensions.html" title="38.17. Packaging Related Objects into an Extension">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="extend.html" title="Chapter 38. Extending SQL">Up</a></td><th width="60%" align="center">Chapter 38. Extending <acronym class="acronym">SQL</acronym></th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 15.7 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="triggers.html" title="Chapter 39. Triggers">Next</a></td></tr></table><hr /></div><div class="sect1" id="EXTEND-PGXS"><div class="titlepage"><div><div><h2 class="title" style="clear: both">38.18. Extension Building Infrastructure</h2></div></div></div><a id="id-1.8.3.21.2" class="indexterm"></a><p>
    If you are thinking about distributing your
    <span class="productname">PostgreSQL</span> extension modules, setting up a
    portable build system for them can be fairly difficult.  Therefore
    the <span class="productname">PostgreSQL</span> installation provides a build
    infrastructure for extensions, called <acronym class="acronym">PGXS</acronym>, so
    that simple extension modules can be built simply against an
    already installed server.  <acronym class="acronym">PGXS</acronym> is mainly intended
    for extensions that include C code, although it can be used for
    pure-SQL extensions too.  Note that <acronym class="acronym">PGXS</acronym> is not
    intended to be a universal build system framework that can be used
    to build any software interfacing to <span class="productname">PostgreSQL</span>;
    it simply automates common build rules for simple server extension
    modules.  For more complicated packages, you might need to write your
    own build system.
   </p><p>
    To use the <acronym class="acronym">PGXS</acronym> infrastructure for your extension,
    you must write a simple makefile.
    In the makefile, you need to set some variables
    and include the global <acronym class="acronym">PGXS</acronym> makefile.
    Here is an example that builds an extension module named
    <code class="literal">isbn_issn</code>, consisting of a shared library containing
    some C code, an extension control file, an SQL script, an include file
    (only needed if other modules might need to access the extension functions
    without going via SQL), and a documentation text file:
</p><pre class="programlisting">
MODULES = isbn_issn
EXTENSION = isbn_issn
DATA = isbn_issn--1.0.sql
DOCS = README.isbn_issn
HEADERS_isbn_issn = isbn_issn.h

PG_CONFIG = pg_config
PGXS := $(shell $(PG_CONFIG) --pgxs)
include $(PGXS)
</pre><p>
    The last three lines should always be the same.  Earlier in the
    file, you assign variables or add custom
    <span class="application">make</span> rules.
   </p><p>
    Set one of these three variables to specify what is built:

    </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="varname">MODULES</code></span></dt><dd><p>
        list of shared-library objects to be built from source files with same
        stem (do not include library suffixes in this list)
       </p></dd><dt><span class="term"><code class="varname">MODULE_big</code></span></dt><dd><p>
        a shared library to build from multiple source files
        (list object files in <code class="varname">OBJS</code>)
       </p></dd><dt><span class="term"><code class="varname">PROGRAM</code></span></dt><dd><p>
        an executable program to build
        (list object files in <code class="varname">OBJS</code>)
       </p></dd></dl></div><p>

    The following variables can also be set:

    </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="varname">EXTENSION</code></span></dt><dd><p>
        extension name(s); for each name you must provide an
        <code class="literal"><em class="replaceable"><code>extension</code></em>.control</code> file,
        which will be installed into
        <code class="literal"><em class="replaceable"><code>prefix</code></em>/share/extension</code>
       </p></dd><dt><span class="term"><code class="varname">MODULEDIR</code></span></dt><dd><p>
        subdirectory of <code class="literal"><em class="replaceable"><code>prefix</code></em>/share</code>
        into which DATA and DOCS files should be installed
        (if not set, default is <code class="literal">extension</code> if
        <code class="varname">EXTENSION</code> is set,
        or <code class="literal">contrib</code> if not)
       </p></dd><dt><span class="term"><code class="varname">DATA</code></span></dt><dd><p>
        random files to install into <code class="literal"><em class="replaceable"><code>prefix</code></em>/share/$MODULEDIR</code>
       </p></dd><dt><span class="term"><code class="varname">DATA_built</code></span></dt><dd><p>
        random files to install into
        <code class="literal"><em class="replaceable"><code>prefix</code></em>/share/$MODULEDIR</code>,
        which need to be built first
       </p></dd><dt><span class="term"><code class="varname">DATA_TSEARCH</code></span></dt><dd><p>
        random files to install under
        <code class="literal"><em class="replaceable"><code>prefix</code></em>/share/tsearch_data</code>
       </p></dd><dt><span class="term"><code class="varname">DOCS</code></span></dt><dd><p>
        random files to install under
        <code class="literal"><em class="replaceable"><code>prefix</code></em>/doc/$MODULEDIR</code>
       </p></dd><dt><span class="term"><code class="varname">HEADERS</code><br /></span><span class="term"><code class="varname">HEADERS_built</code></span></dt><dd><p>
        Files to (optionally build and) install under
        <code class="literal"><em class="replaceable"><code>prefix</code></em>/include/server/$MODULEDIR/$MODULE_big</code>.
       </p><p>
        Unlike <code class="literal">DATA_built</code>, files in <code class="literal">HEADERS_built</code>
        are not removed by the <code class="literal">clean</code> target; if you want them removed,
        also add them to <code class="literal">EXTRA_CLEAN</code> or add your own rules to do it.
       </p></dd><dt><span class="term"><code class="varname">HEADERS_$MODULE</code><br /></span><span class="term"><code class="varname">HEADERS_built_$MODULE</code></span></dt><dd><p>
        Files to install (after building if specified) under
        <code class="literal"><em class="replaceable"><code>prefix</code></em>/include/server/$MODULEDIR/$MODULE</code>,
        where <code class="literal">$MODULE</code> must be a module name used
        in <code class="literal">MODULES</code> or <code class="literal">MODULE_big</code>.
       </p><p>
        Unlike <code class="literal">DATA_built</code>, files in <code class="literal">HEADERS_built_$MODULE</code>
        are not removed by the <code class="literal">clean</code> target; if you want them removed,
        also add them to <code class="literal">EXTRA_CLEAN</code> or add your own rules to do it.
       </p><p>
        It is legal to use both variables for the same module, or any
        combination, unless you have two module names in the
        <code class="literal">MODULES</code> list that differ only by the presence of a
        prefix <code class="literal">built_</code>, which would cause ambiguity. In
        that (hopefully unlikely) case, you should use only the
        <code class="literal">HEADERS_built_$MODULE</code> variables.
       </p></dd><dt><span class="term"><code class="varname">SCRIPTS</code></span></dt><dd><p>
        script files (not binaries) to install into
        <code class="literal"><em class="replaceable"><code>prefix</code></em>/bin</code>
       </p></dd><dt><span class="term"><code class="varname">SCRIPTS_built</code></span></dt><dd><p>
        script files (not binaries) to install into
        <code class="literal"><em class="replaceable"><code>prefix</code></em>/bin</code>,
        which need to be built first
       </p></dd><dt><span class="term"><code class="varname">REGRESS</code></span></dt><dd><p>
        list of regression test cases (without suffix), see below
       </p></dd><dt><span class="term"><code class="varname">REGRESS_OPTS</code></span></dt><dd><p>
        additional switches to pass to <span class="application">pg_regress</span>
       </p></dd><dt><span class="term"><code class="varname">ISOLATION</code></span></dt><dd><p>
        list of isolation test cases, see below for more details
       </p></dd><dt><span class="term"><code class="varname">ISOLATION_OPTS</code></span></dt><dd><p>
        additional switches to pass to
        <span class="application">pg_isolation_regress</span>
       </p></dd><dt><span class="term"><code class="varname">TAP_TESTS</code></span></dt><dd><p>
        switch defining if TAP tests need to be run, see below
       </p></dd><dt><span class="term"><code class="varname">NO_INSTALL</code></span></dt><dd><p>
        don't define an <code class="literal">install</code> target, useful for test
        modules that don't need their build products to be installed
       </p></dd><dt><span class="term"><code class="varname">NO_INSTALLCHECK</code></span></dt><dd><p>
        don't define an <code class="literal">installcheck</code> target, useful e.g., if tests require special configuration, or don't use <span class="application">pg_regress</span>
       </p></dd><dt><span class="term"><code class="varname">EXTRA_CLEAN</code></span></dt><dd><p>
        extra files to remove in <code class="literal">make clean</code>
       </p></dd><dt><span class="term"><code class="varname">PG_CPPFLAGS</code></span></dt><dd><p>
        will be prepended to <code class="varname">CPPFLAGS</code>
       </p></dd><dt><span class="term"><code class="varname">PG_CFLAGS</code></span></dt><dd><p>
        will be appended to <code class="varname">CFLAGS</code>
       </p></dd><dt><span class="term"><code class="varname">PG_CXXFLAGS</code></span></dt><dd><p>
        will be appended to <code class="varname">CXXFLAGS</code>
       </p></dd><dt><span class="term"><code class="varname">PG_LDFLAGS</code></span></dt><dd><p>
        will be prepended to <code class="varname">LDFLAGS</code>
       </p></dd><dt><span class="term"><code class="varname">PG_LIBS</code></span></dt><dd><p>
        will be added to <code class="varname">PROGRAM</code> link line
       </p></dd><dt><span class="term"><code class="varname">SHLIB_LINK</code></span></dt><dd><p>
        will be added to <code class="varname">MODULE_big</code> link line
       </p></dd><dt><span class="term"><code class="varname">PG_CONFIG</code></span></dt><dd><p>
        path to <span class="application">pg_config</span> program for the
        <span class="productname">PostgreSQL</span> installation to build against
        (typically just <code class="literal">pg_config</code> to use the first one in your
        <code class="varname">PATH</code>)
       </p></dd></dl></div><p>
   </p><p>
    Put this makefile as <code class="literal">Makefile</code> in the directory
    which holds your extension. Then you can do
    <code class="literal">make</code> to compile, and then <code class="literal">make
    install</code> to install your module.  By default, the extension is
    compiled and installed for the
    <span class="productname">PostgreSQL</span> installation that
    corresponds to the first <code class="command">pg_config</code> program
    found in your <code class="varname">PATH</code>.  You can use a different installation by
    setting <code class="varname">PG_CONFIG</code> to point to its
    <code class="command">pg_config</code> program, either within the makefile
    or on the <code class="literal">make</code> command line.
   </p><p>
    You can also run <code class="literal">make</code> in a directory outside the source
    tree of your extension, if you want to keep the build directory separate.
    This procedure is also called a
    <a id="id-1.8.3.21.7.2" class="indexterm"></a><em class="firstterm">VPATH</em>
    build.  Here's how:
</p><pre class="programlisting">
mkdir build_dir
cd build_dir
make -f /path/to/extension/source/tree/Makefile
make -f /path/to/extension/source/tree/Makefile install
</pre><p>
   </p><p>
    Alternatively, you can set up a directory for a VPATH build in a similar
    way to how it is done for the core code. One way to do this is using the
    core script <code class="filename">config/prep_buildtree</code>. Once this has been done
    you can build by setting the <code class="literal">make</code> variable
    <code class="varname">VPATH</code> like this:
</p><pre class="programlisting">
make VPATH=/path/to/extension/source/tree
make VPATH=/path/to/extension/source/tree install
</pre><p>
    This procedure can work with a greater variety of directory layouts.
   </p><p>
    The scripts listed in the <code class="varname">REGRESS</code> variable are used for
    regression testing of your module, which can be invoked by <code class="literal">make
    installcheck</code> after doing <code class="literal">make install</code>.  For this to
    work you must have a running <span class="productname">PostgreSQL</span> server.
    The script files listed in <code class="varname">REGRESS</code> must appear in a
    subdirectory named <code class="literal">sql/</code> in your extension's directory.
    These files must have extension <code class="literal">.sql</code>, which must not be
    included in the <code class="varname">REGRESS</code> list in the makefile.  For each
    test there should also be a file containing the expected output in a
    subdirectory named <code class="literal">expected/</code>, with the same stem and
    extension <code class="literal">.out</code>.  <code class="literal">make installcheck</code>
    executes each test script with <span class="application">psql</span>, and compares the
    resulting output to the matching expected file.  Any differences will be
    written to the file <code class="literal">regression.diffs</code> in <code class="command">diff
    -c</code> format.  Note that trying to run a test that is missing its
    expected file will be reported as <span class="quote"><span class="quote">trouble</span></span>, so make sure you
    have all expected files.
   </p><p>
    The scripts listed in the <code class="varname">ISOLATION</code> variable are used
    for tests stressing behavior of concurrent session with your module, which
    can be invoked by <code class="literal">make installcheck</code> after doing
    <code class="literal">make install</code>.  For this to work you must have a
    running <span class="productname">PostgreSQL</span> server.  The script files
    listed in <code class="varname">ISOLATION</code> must appear in a subdirectory
    named <code class="literal">specs/</code> in your extension's directory.  These files
    must have extension <code class="literal">.spec</code>, which must not be included
    in the <code class="varname">ISOLATION</code> list in the makefile.  For each test
    there should also be a file containing the expected output in a
    subdirectory named <code class="literal">expected/</code>, with the same stem and
    extension <code class="literal">.out</code>.  <code class="literal">make installcheck</code>
    executes each test script, and compares the resulting output to the
    matching expected file.  Any differences will be written to the file
    <code class="literal">output_iso/regression.diffs</code> in
    <code class="command">diff -c</code> format.  Note that trying to run a test that is
    missing its expected file will be reported as <span class="quote"><span class="quote">trouble</span></span>, so
    make sure you have all expected files.
   </p><p>
    <code class="literal">TAP_TESTS</code> enables the use of TAP tests.  Data from each
    run is present in a subdirectory named <code class="literal">tmp_check/</code>.
    See also <a class="xref" href="regress-tap.html" title="33.4. TAP Tests">Section 33.4</a> for more details.
   </p><div class="tip"><h3 class="title">Tip</h3><p>
     The easiest way to create the expected files is to create empty files,
     then do a test run (which will of course report differences).  Inspect
     the actual result files found in the <code class="literal">results/</code>
     directory (for tests in <code class="literal">REGRESS</code>), or
     <code class="literal">output_iso/results/</code> directory (for tests in
     <code class="literal">ISOLATION</code>), then copy them to
     <code class="literal">expected/</code> if they match what you expect from the test.
    </p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="extend-extensions.html" title="38.17. Packaging Related Objects into an Extension">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="extend.html" title="Chapter 38. Extending SQL">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="triggers.html" title="Chapter 39. Triggers">Next</a></td></tr><tr><td width="40%" align="left" valign="top">38.17. Packaging Related Objects into an Extension </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 15.7 Documentation">Home</a></td><td width="40%" align="right" valign="top"> Chapter 39. Triggers</td></tr></table></div></body></html>