[CDBI] Make CDBI go fast

Perrin Harkins pharkins at gmail.com
Wed Mar 21 14:17:51 GMT 2007


On 3/21/07, Brad Bowman <list at bereft.net> wrote:
> Does MySQL sort the entire file to get the first 11?  Do other databases?

It's not possible to know what the first 11 are without sorting them
at some point.  Most databases, including MySQL, use indexes to speed
up sorting when possible.  In the best case, this amounts to
pre-sorting the results.  The filesort only happens when MySQL is not
able to find an index it can use for the requested sort order.

- Perrin



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