Hi!
>>>>> "Ulf" == Ulf Harnhammar <[EMAIL PROTECTED]> writes: Ulf> On Sun, 27 Jan 2002, Michael Widenius wrote: >> One way to do this is to do as follows: >> SELECT something FROM sometable WHERE somevar=somevalue ORDER BY >> RAND() LIMIT 10 Ulf> OK. I still think that my extended LIMIT syntax would be a good idea, Ulf> because ORDER BY RAND() does not seem to be very fast. If you want to have a true random order of rows, MySQL must first find all the rows that matches the where clause. Compared to that, the speed of ORDER BY and LIMIT is normally neglectable! (MySQL do also optimize ORDER BY combined with LIMIT fairly well) Ulf> I tried adding a field that numbers all instances of a certain ID (this Ulf> probably breaks some normalization rule). This way I could simulate what Ulf> things would be like with an extended LIMIT syntax. This SQL statement: Ulf> SELECT varWord FROM dictionaryword WHERE intTypeID='11' AND Ulf> (intTypeCounter<26) Ulf> executed a lot faster than: Ulf> SELECT varWord FROM dictionaryword WHERE intTypeID='11' ORDER BY RAND() Ulf> LIMIT 25 The queries are not comparable as the second query will have to first retrieve all the rows, not just those that has been previously marked. Another thing is that the second query will every time return a different set of rows, which is probably what you want in the first place. Ulf> Thus, I still think it would be a good idea to be able to say: Ulf> SELECT COUNT(*) AS greve FROM dictionaryword WHERE intTypeID='11' Ulf> and then: Ulf> SELECT varWord FROM dictionaryword WHERE intTypeID='11' LIMIT number1,1, Ulf> number2,1,number3,1,number4,1,.. Which would in almost all cases be much slower than doing ORDER BY RAND. Regards, Monty --------------------------------------------------------------------- Before posting, please check: http://www.mysql.com/manual.php (the manual) http://lists.mysql.com/ (the list archive) To request this thread, e-mail <[EMAIL PROTECTED]> To unsubscribe, e-mail <[EMAIL PROTECTED]> Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php
