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Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/plperl.sgml | 50 |
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diff --git a/doc/src/sgml/plperl.sgml b/doc/src/sgml/plperl.sgml index 10eac0e243c..34663e475fe 100644 --- a/doc/src/sgml/plperl.sgml +++ b/doc/src/sgml/plperl.sgml @@ -1211,6 +1211,56 @@ CREATE TRIGGER test_valid_id_trig </para> </sect1> + <sect1 id="plperl-event-triggers"> + <title>PL/Perl Event Triggers</title> + + <para> + PL/Perl can be used to write event trigger functions. In an event trigger + function, the hash reference <varname>$_TD</varname> contains information + about the current trigger event. <varname>$_TD</> is a global variable, + which gets a separate local value for each invocation of the trigger. The + fields of the <varname>$_TD</varname> hash reference are: + + <variablelist> + <varlistentry> + <term><literal>$_TD->{event}</literal></term> + <listitem> + <para> + The name of the event the trigger is fired for. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><literal>$_TD->{tag}</literal></term> + <listitem> + <para> + The command tag for which the trigger is fired. + </para> + </listitem> + </varlistentry> + </variablelist> + </para> + + <para> + The return value of the trigger procedure is ignored. + </para> + + <para> + Here is an example of an event trigger function, illustrating some of the + above: +<programlisting> +CREATE OR REPLACE FUNCTION perlsnitch() RETURNS event_trigger AS $$ + elog(NOTICE, "perlsnitch: " . $_TD->{event} . " " . $_TD->{tag} . " "); +$$ LANGUAGE plperl; + +CREATE EVENT TRIGGER perl_a_snitch + ON ddl_command_start + EXECUTE PROCEDURE perlsnitch(); +</programlisting> + </para> + </sect1> + <sect1 id="plperl-under-the-hood"> <title>PL/Perl Under the Hood</title> |