Last Modified: 10.10.2012
The most important parameter that affects the amount of memory required by database (MySQL\Oracle) is the maximum number of simultaneous connections ("max_connections").
The use of a two-tier architecture can decrease the number of concurrent database connection several times less and give more memory for data sorting and buffering.
If you specify the MaxClients value in the back-end web server settings, you guarantee that the maximum database connections equals the maximum number of simultaneous web client connections. Consequently, the number of connections is fixed!
Choose the value of the max_connections parameter such that the system has 10% to 20% of maximum connections in reserve. In other words, set max_connections to a value 10% to 20% more than MaxClients.