Re: subqueries vs. separate queries
От | Christopher Browne |
---|---|
Тема | Re: subqueries vs. separate queries |
Дата | |
Msg-id | 60ad462xk1.fsf@dev6.int.libertyrms.info обсуждение исходный текст |
Ответ на | subqueries vs. separate queries (CSN <cool_screen_name90001@yahoo.com>) |
Список | pgsql-general |
cool_screen_name90001@yahoo.com (CSN) writes: > Is there much difference between using subqueries and separating out > them into separate queries? Yes. No. Maybe. What kind of difference are you thinking about? If you join queries together, you wind up with fewer queries, and your outside code that manipulates the results will likely have less work to do. There are certainly notions of "efficiency" and "simplicity" that can out of that. By the same token, those fewer queries are sure to be a bit more complex, may be more difficult to write and understand, and may poke at "edges" of the query optimizer such that they _may_, if you are very unlucky, run unexpectedly slowly. It is quite possible for the simplifications of your application to outweigh the _possible_ costs... -- output = ("cbbrowne" "@" "ntlug.org") http://cbbrowne.com/info/linux.html Would-be National Mottos: USA: "We don't care where you come from. We can't find our *own* country on a map..."
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