From 9e84cccff28e52ab76aa3d3e88bd815dc36d24d8 Mon Sep 17 00:00:00 2001
From: Bruce Momjian <bruce@momjian.us>
Date: Tue, 14 Aug 2012 23:21:13 -0400
Subject: [PATCH] Add doc example of restricting large object trigger firing to
only updates of the column of interest.
---
doc/src/sgml/lo.sgml | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/doc/src/sgml/lo.sgml b/doc/src/sgml/lo.sgml
index 3d56ba3f70a..0c11fdc20aa 100644
--- a/doc/src/sgml/lo.sgml
+++ b/doc/src/sgml/lo.sgml
@@ -76,7 +76,15 @@ CREATE TRIGGER t_raster BEFORE UPDATE OR DELETE ON image
<para>
For each column that will contain unique references to large objects,
create a <literal>BEFORE UPDATE OR DELETE</> trigger, and give the column
- name as the sole trigger argument. If you need multiple <type>lo</>
+ name as the sole trigger argument. You can also restrict the trigger
+ to only execute on updates to the column with:
+
+<programlisting>
+CREATE TRIGGER t_raster BEFORE UPDATE OF raster OR DELETE ON image
+ FOR EACH ROW EXECUTE PROCEDURE lo_manage(raster);
+</programlisting>
+
+ If you need multiple <type>lo</>
columns in the same table, create a separate trigger for each one,
remembering to give a different name to each trigger on the same table.
</para>
--
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