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Support SQL-compliant triggers on columns, ie fire only if certain columns

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are named in the UPDATE's SET list.

Note: the schema of pg_trigger has not actually changed; we've just started
to use a column that was there all along.  catversion bumped anyway so that
this commit is included in the history of potentially interesting changes
to system catalog contents.

Itagaki Takahiro
This commit is contained in:
Tom Lane
2009-10-14 22:14:25 +00:00
parent be922e8555
commit b2734a0d79
17 changed files with 433 additions and 183 deletions
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13
doc/src/sgml/trigger.sgml
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@@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/trigger.sgml,v 1.58 2009/08/04 22:04:37 petere Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/trigger.sgml,v 1.59 2009/10/14 22:14:21 tgl Exp $ -->
<chapter id="triggers">
<title>Triggers</title>
@@ -36,10 +36,13 @@
performed. Triggers can be defined to execute either before or after any
<command>INSERT</command>, <command>UPDATE</command>, or
<command>DELETE</command> operation, either once per modified row,
or once per <acronym>SQL</acronym> statement. Triggers can also fire
for <command>TRUNCATE</command> statements. If a trigger event occurs,
the trigger's function is called at the appropriate time to handle the
event.
or once per <acronym>SQL</acronym> statement.
<command>UPDATE</command> triggers can moreover be set to fire only if
certain columns are mentioned in the <literal>SET</literal> clause of the
<command>UPDATE</command> statement.
Triggers can also fire for <command>TRUNCATE</command> statements.
If a trigger event occurs, the trigger's function is called at the
appropriate time to handle the event.
</para>
<para>