HOBALL 筆記簿

March 30, 2010

How MySQL executes ORDER BY

Filed under: SQL — Tags: , — hoball @ 3:30 pm

Reference: http://s.petrunia.net/blog/?p=24

November 6, 2009

MySQL changing runtime variables without restart

Filed under: SQL — Tags: , , — hoball @ 5:18 pm

Setting Global variable, the followings are identical. (effective until service restart)

mysql> SET GLOBAL long_query_time = 3;
mysql> SET @@global. long_query_time = 3;

Setting Session variable, the followings are identical.  (effective until your session ends. Changes are not visible to other clients) 

mysql> SET SESSION long_query_time = 3;
mysql> SET @@session. long_query_time = 3;
mysql> SET @@long_query_time = 3;

More: MySQL.com Dynamic system variables

Reference: http://crazytoon.com/2007/07/23/mysql-changing-runtime-variables-with-out-restarting-mysql-server/

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