On Wed, Nov 16, 2005 at 10:31:10AM +0200, Sarunas Krisciukaitis wrote:
> I understand that RULES are like macros.
> Strangest thing here is that INSERT to test1 will touch only one
> sequence: test1_id_seq.
> And it increments test1_id_seq twice during insert with RULE.
Yes, that's a well-known effect of rewriting a query that includes
a call to nextval(). NEW.id in the rule doesn't refer to the value
that's inserted, but rather to the expression that's evaluated to
get that value. Since you didn't provide a value for id it gets
the default: nextval('test1_id_seq'). That expression is used in
both inserts, so the sequence gets incremented twice. See the
archives for numerous past discussions of this behavior.
--
Michael Fuhr
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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
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