Hi!
On Dec 05, tk wrote:
> Hello Sergei, Gunnar, and others,
>
> thank you for your quick responses.
> One little mystery remains:
>
> Why does one need to read all the row data (with
> SQL_CALC_FOUND_ROWS) to get the total number of
> results when using a limit?
>
> When the index is used to find relevant rows and sort
> the results, the code certainly must know how many
> total results there are.
Yes, but it's different code, it works on a different level and knows
nothing about SQL_CALC_FOUND_ROWS :(
> Could one not store the total while using the index
> and use "select FOUND_ROWS()" without
> SQL_CALC_FOUND_ROWS to retrieve the total?
Yes, it could.
It is the optimization that wasn't implemented yet.
(but it's in the TODO)
Regards,
Sergei
--
__ ___ ___ ____ __
/ |/ /_ __/ __/ __ \/ / Sergei Golubchik <serg@stripped>
/ /|_/ / // /\ \/ /_/ / /__ MySQL AB, Senior Software Developer
/_/ /_/\_, /___/\___\_\___/ Osnabrueck, Germany
<___/ www.mysql.com
