On Mon, May 19, 2008 at 08:19:17AM +0200, Zoltan Boszormenyi wrote: > >The standard has a clause to specify depth-first order. However doing a > >depth-first traversal would necessitate quite a different looking plan and > >it's far less obvious (to me anyways) how to do it. > > That would be even cooler to have it implemented as well.
From an implementation point of view, the only difference between breadth-first and depth-first is that your tuplestore needs to be LIFO instead of FIFO. However, just looking at the plan I don't know whether it could support that kind of usage. At the very least I don't think the standard tuplestore code can handle it. > >Well, psql might wait and wait but it's actually receiving rows. A cleverer > >client should be able to deal with infinite streams of records. > > I think it's the other way around. The server should not emit infinite > number of records. The server won't, the universe will end first. This is a nice example of the halting problem: http://en.wikipedia.org/wiki/Halting_problem Which was proved unsolvable a long time ago. Have a nice day, -- Martijn van Oosterhout <[EMAIL PROTECTED]> 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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