"Nico Callewaert" <nico.callewaert@ets-informatics.com> writes: > I don't understand the difference between the following syntax : > CREATE FUNCTION "test_check_a_id" () RETURNS opaque AS ' > CREATE FUNCTION LAST_UPDATED() RETURNS "trigger" AS $$ > Especially the difference between opaque and "trigger". Trigger is the recommended way of declaring triggers. Opaque was the way to do it before we invented the separate trigger pseudo-type (which happened in 7.3 IIRC ... a long time ago, anyway). Opaque was serving so many different purposes that we felt it needed to be split up --- see the table in http://www.postgresql.org/docs/8.2/static/datatype-pseudo.html > And the double quotes, seems sometimes used and sometimes not. They don't make any difference in the above example. See http://www.postgresql.org/docs/8.2/static/sql-syntax-lexical.html#SQL-SYNTAX-IDENTIFIERS regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match