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Add plperl.on_perl_init setting to provide for initializing the perl library on load. Also, handle END blocks in plperl.

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Database access is disallowed during both these operations, although it might be allowed in END blocks in future.

Patch from Tim Bunce.
This commit is contained in:
Andrew Dunstan
2010-01-30 01:46:57 +00:00
parent 29eedd3122
commit 85d67ccd75
5 changed files with 272 additions and 22 deletions
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82
doc/src/sgml/plperl.sgml
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@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/plperl.sgml,v 2.76 2010/01/27 02:55:04 adunstan Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/plperl.sgml,v 2.77 2010/01/30 01:46:57 adunstan Exp $ -->
<chapter id="plperl">
<title>PL/Perl - Perl Procedural Language</title>
@ -1028,7 +1028,72 @@ CREATE TRIGGER test_valid_id_trig
</para>
</sect1>
<sect1 id="plperl-missing">
<sect1 id="plperl-under-the-hood">
<title>PL/Perl Under the Hood</title>
<sect2 id="plperl-config">
<title>Configuration</title>
<para>
This section lists configuration parameters that affect <application>PL/Perl</>.
To set any of these parameters before <application>PL/Perl</> has been loaded,
it is necessary to have added <quote><literal>plperl</></> to the
<xref linkend="guc-custom-variable-classes"> list in
<filename>postgresql.conf</filename>.
</para>
<variablelist>
<varlistentry id="guc-plperl-on-perl-init" xreflabel="plperl.on_perl_init">
<term><varname>plperl.on_perl_init</varname> (<type>string</type>)</term>
<indexterm>
<primary><varname>plperl.on_perl_init</> configuration parameter</primary>
</indexterm>
<listitem>
<para>
Specifies perl code to be executed when a perl interpreter is first initialized.
The SPI functions are not available when this code is executed.
If the code fails with an error it will abort the initialization of the interpreter
and propagate out to the calling query, causing the current transaction
or subtransaction to be aborted.
</para>
<para>
The perl code is limited to a single string. Longer code can be placed
into a module and loaded by the <literal>on_perl_init</> string.
Examples:
<programlisting>
plplerl.on_perl_init = '$ENV{NYTPROF}="start=no"; require Devel::NYTProf::PgPLPerl'
plplerl.on_perl_init = 'use lib "/my/app"; use MyApp::PgInit;'
</programlisting>
</para>
<para>
Initialization will happen in the postmaster if the plperl library is included
in <literal>shared_preload_libraries</> (see <xref linkend="guc-shared-preload-libraries">),
in which case extra consideration should be given to the risk of destabilizing the postmaster.
</para>
<para>
This parameter can only be set in the postgresql.conf file or on the server command line.
</para>
</listitem>
</varlistentry>
<varlistentry id="guc-plperl-use-strict" xreflabel="plperl.use_strict">
<term><varname>plperl.use_strict</varname> (<type>boolean</type>)</term>
<indexterm>
<primary><varname>plperl.use_strict</> configuration parameter</primary>
</indexterm>
<listitem>
<para>
When set true subsequent compilations of PL/Perl functions have the <literal>strict</> pragma enabled.
This parameter does not affect functions already compiled in the current session.
</para>
</listitem>
</varlistentry>
</variablelist>
</sect2>
<sect2 id="plperl-missing">
<title>Limitations and Missing Features</title>
<para>
@ -1063,10 +1128,21 @@ CREATE TRIGGER test_valid_id_trig
<literal>return_next</literal> for each row returned, as shown
previously.
</para>
</listitem>
<listitem>
<para>
When a session ends normally, not due to a fatal error, any
<literal>END</> blocks that have been defined are executed.
Currently no other actions are performed. Specifically,
file handles are not automatically flushed and objects are
not automatically destroyed.
</para>
</listitem>
</itemizedlist>
</para>
</sect2>
</sect1>
</chapter>