Re: large temp files created by mysql

[Reindl Harald]

Am 24.10.2011 18:02, schrieb mos:
> At 10:34 AM 10/24/2011, you wrote:
>> select id from table order by rand() limit 1;
>> is doing as example a dumb temporary table with the full size
> 
> Because it has to sort the entire table, then it returns the one row. This of 
> course is extremely inefficient. :)
> You need to choose a random row by using an auto-inc field. Something like:
> 
> select id from table where id>=myrandomnum limit 1

but this is TOTALLY braindead if "id" is a primary-KEY with auto-increment

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