Re: Re: RANDOM function?
От | Einar Karttunen |
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Тема | Re: Re: RANDOM function? |
Дата | |
Msg-id | Pine.LNX.4.33.0107311627520.20135-100000@melkinpaasi.cs.Helsinki.FI обсуждение исходный текст |
Ответ на | Re: Re: RANDOM function? (ghaverla@freenet.edmonton.ab.ca) |
Список | pgsql-novice |
On Tue, 31 Jul 2001 ghaverla@freenet.edmonton.ab.ca wrote: > > I'm sure you can do a search for a RNG without replacement as > easily as I can. Yes, a person can always keep track of what > numbers have already been picked and reject duplicate picks. > If the number of picks you are making is much smaller than the > space you are picking from, this would work fine. Especially > using a smart (not linear) search for the possible duplicate. > If the number of picks is getting close to the size of the > stack, rejection is going to be a big loser. Any program > that draws cards from a deck is going to use this type of > without replacement method, as some card games deal the entire > deck. I don't think it is wise to do it externally if you can let the db do it using unique columns. The method you suggested just sounded new to me, I would have preferred a hash table or a tree structure. - Einar Karttunen
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