On Nov 22, 2009, at 8:54 AM, Ryan Chan wrote:
Hello, Is it common heard from people that if you have large table (assume MyISAM in my case), you need large memory in order to have the key/index in memory for performance, otherwise, table scan on disk is slow. But how to estimate how much memory I need? Consider a simple case, a MyISAM table is 10GB in size, with 2GB index, how much memory I need? Thanks.
It's not the size of the table, it's the size of the index that you need to watch. MyISAM keeps the table and index separate, so the memory requirements can be considerably less than the size of the table. What you have likely heard is in reference to InnoDB tables. Since InnoDB "clusters" the index with the data, the memory requirements can be much greater. You may notice a significant drop off in performance from InnoDB once the data size passes a certain level, which is based on your RAM and InnoDB settings. MyISAM performance is usually fairy steady as the size of the table increases.
-- Brent Baisley -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/mysql?unsub=arch...@jab.org
