On Mon, Oct 05, 2009 at 10:32:53AM -0400, Tom Lane wrote: > Martijn van Oosterhout <klep...@svana.org> writes: > > WITH NEW AS ( > > insert into t values (floor(random()*1000)::integer); > > RETURNING * > > ) > > insert into t_log values (NEW.a); > > > Would this not have the required semantics? > > Interesting idea, but it's not clear how to make it work with multiple > DO ALSO rules, nor with conditional DO INSTEAD rules.
Well, my (possibly naive) view is: - Multiple DO ALSO rules seem easy. There is a patch in the works which makes INSERT/UPDATE/DELETE into proper node types so they can actually appear in the WITH clause above. With a minor extension you could create a MultipleStatement node type which merely runs each substatement, like Append, but for plans. - Conditional DO INSTEAD rules are brain benders. Logically, I think they split the plan in two, one with the condition, one with the negative of the condition. So *maybe* they could also be handled by such a MultipleStatement node but then... I get visions of people writing a SELECT rule with a conditional DELETE statement with RETURNING *. Then, SELECTing the table would return everything but conditionally DELETE some rows. Something like: WITH OLD AS (SELECT * FROM foo) MULTISTATEMENT( SELECT * FROM OLD WHERE condition; DELETE FROM OLD WHERE NOT condition RETURNING *; ) As for actual implementation it seems doable, but I may be being impossibly naive. Have a nice day, -- Martijn van Oosterhout <klep...@svana.org> http://svana.org/kleptog/ > Please line up in a tree and maintain the heap invariant while > boarding. Thank you for flying nlogn airlines.
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