Re: Am I really stupid???
От | Dragos Stoichita |
---|---|
Тема | Re: Am I really stupid??? |
Дата | |
Msg-id | SAK.2000.05.17.rkniftej@ddd обсуждение исходный текст |
Список | pgsql-general |
Original message from: Fabrice Scemama >On finit par penser que ta question comporte en elle >sa propre reponse :-) >informe-toi sur les joins en particulier et le SQL en general. >Tu critiqueras la liste et les gens ensuite. > >(translation to English-speaking mailing-list users: > I replied 'RTFM' :-) > >Fabrice Scemama > >Dragos Stoichita wrote: Let's get rid of those kind of messages. When you write a message saying you are a beginner, there's always a little bunch of people like you who particularly like to say: "go read the docs newbie" or "go learn that" etc. I am not someone who never reads the docs before asking a question. I know SQL, I know joins, and all the people who told me to rewrite the query would better have not answered my message, because I already knew that. I take your message as a personal insult, because I don't criticize people without reason, and I did criticize this list because it was justified. I need help about only once every 2 or three months, because I am able to use the docs and do my own work alone. HERE I AM NOT ASKING HELP! I asked a simple question: why the query with intersects is not only slower, but with a factor of 10^something slower than the join one. If the select returns a table of 1 column with n rows all integers, sorting them ~n*logn, unique is ~n and intersect is ~n. I have here a book on Algorithmics and have validated a course on this, I know what I talk about. Why, with performant sorting, unique and intersect algorithms, it takes 13 seconds??? I just want a real serious person that has knowledge to answer this precise question, using an algorithmic demonstration. I only talk about maths and algorithms here. Please be serious in your answer next time. Dragos Stoichita.
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