On Tue, Apr 01, 2008 at 06:06:35PM +0200, Ivan Sergio Borgonovo wrote: > Would you please be so kind to rephrase: > > http://www.postgresql.org/docs/8.1/interactive/xfunc-volatility.html <snip> > I can't understand how it can call a function a single time and avoid > to cache the result. > Is it limited to a single statement? Yes, it's limited to a single statememnt. Let's say hypothetically postgres could optimise: select f() + f(); to select 2*f(); It would have to optimised so it only calls the function once yet at no time does it "cache" the result in the usual sense. Does this helps, > select into bau cetti from stablefunc(sameparam); > > select into bingo t.bongo from stablefunc(sameparam) as s > join sometable t on s.cetti=t.cetti; > > will call stablefunc 2 times? Yes. > So... then any pointer to some places where I could learn some > caching techniques if STABLE doesn't do the trick? Anything persistnat usually needs to be in a table. If it's a really small amount you could use the global namespace in pl/perl or similar in other languages. Have a nice day, -- Martijn van Oosterhout <kleptog@xxxxxxxxx> 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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