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Add doc example of restricting large object trigger firing to only 

updates of the column of interest.
This commit is contained in:
Bruce Momjian 2012-08-14 23:21:13 -04:00
parent e45ae40181
commit 9e84cccff2
1 changed files with 9 additions and 1 deletions
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10
doc/src/sgml/lo.sgml
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@ -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>