One possibility is that the OS has the portion of disk that the row is stored in cached in memory via its normal disk caching after the first execution. Another possibility is that the key for the table is in mysql's key_buffer after the first execution. If you are using innodb then it might be cached in the buffer_pool. There are quite a few levels of caching going on at the mysql and os level and they all need to be considered.
John A. McCaskey -----Original Message----- From: Boyd E. Hemphill [mailto:[EMAIL PROTECTED] Sent: Tuesday, April 27, 2004 12:41 PM To: [EMAIL PROTECTED] Subject: sql_no_cache I am trying to turn of the query caching for select queries I am testing as I would like to rerun the as if they were the first hit. The query-cache-type = 1. I am suspicious b/c I run a query and it takes 12 seconds. I then run the same query with no changes and it takes .17 seconds. Another piece to this puzzle might be that when I issued the FLUSH QUERY CACHE command and then reran the query and it still took a very short time. Since this is a devel server and I am the only one around I don't think there are any other obvious things going on. Mytop is clear of processes. Am I missing something? Boyd E. Hemphill -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED] -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
