Hello pgdevs,
The very minor patch attached improves the PL/pgSQL documentation about
trigger functions. It moves the description common to both data change &
database event triggers out of the first section and into a common header.
It adds a link at the beginning of the sections to their corresponding
generic chapters.
--
Fabien.
diff --git a/doc/src/sgml/plpgsql.sgml b/doc/src/sgml/plpgsql.sgml
index 7f23c2f..5d4080f 100644
--- a/doc/src/sgml/plpgsql.sgml
+++ b/doc/src/sgml/plpgsql.sgml
@@ -3660,18 +3660,26 @@ ASSERT <replaceable class="parameter">condition</replaceable> <optional> , <repl
<secondary>in PL/pgSQL</secondary>
</indexterm>
+ <para>
+ <application>PL/pgSQL</application> can be used to define trigger
+ procedures on data changes or database events.
+ A trigger procedure is created with the <command>CREATE FUNCTION</> command,
+ declaring it as a function with no arguments and a return type of
+ <type>trigger</> (for data change triggers) or
+ <type>event_trigger</> (for database event triggers).
+ Special variables <varname>PG_<replaceable>something</></> are automatically
+ available to test the condition which triggered the call.
+ </para>
+
<sect2 id="plpgsql-dml-trigger">
<title>Triggers on Data Changes</title>
- <para>
- <application>PL/pgSQL</application> can be used to define trigger
- procedures. A trigger procedure is created with the
- <command>CREATE FUNCTION</> command, declaring it as a function with
- no arguments and a return type of <type>trigger</type>. Note that
- the function must be declared with no arguments even if it expects
- to receive arguments specified in <command>CREATE TRIGGER</> —
- trigger arguments are passed via <varname>TG_ARGV</>, as described
- below.
+ <para>
+ A <link linkend="triggers">data change trigger</> is declared as a function
+ with no arguments and a return type of <type>trigger</>.
+ Note that the function must be declared with no arguments even if it expects
+ to receive arguments specified in <command>CREATE TRIGGER</> —
+ trigger arguments are passed via <varname>TG_ARGV</>, as described below.
</para>
<para>
@@ -4218,8 +4226,9 @@ SELECT * FROM sales_summary_bytime;
<title>Triggers on Events</title>
<para>
- <application>PL/pgSQL</application> can be used to define event
- triggers. <productname>PostgreSQL</> requires that a procedure that
+ <application>PL/pgSQL</application> can be used to define
+ <link linkend="event-triggers">event triggers</>.
+ <productname>PostgreSQL</> requires that a procedure that
is to be called as an event trigger must be declared as a function with
no arguments and a return type of <literal>event_trigger</>.
</para>
--
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