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. 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>
-
+ to only execute on updates to the column by using <literal>BEFORE UPDATE
+ OF</literal> <replaceable class="parameter">column_name</replaceable>.
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.