Hi!
"MARK" == MARK CALLAGHAN <mdcallag@gmail.com> writes:
MARK> What are the difference between logical and physical IO? I assume you MARK> are using Oracle's terminology where a logical IO means that a page MARK> was read from the InnoDB buffer cache. MARK> On Thu, Dec 29, 2011 at 6:41 PM, jiangchengyao <jiangchengyao@gmail.com> wrote:
Hi, all
I write a patch to show physical & logical IO statistics in slow log. Now it only support XtraDB storage engine, but it is easy to realize in other engine. You may found it like this in slow log:
# Time: 111227 16:29:54 # User@Host: root[root] @ localhost [::1] # Query_time: 0.310018 Lock_time: 0.203012 Rows_sent: 1 Rows_examined: 30000 Logical_IO: 30145 Physical_IO: 50
I assume it's number of IO from that comes from the page cache (not really an IO) and the number of IO that comes from doing a read() call. I will know more when I have looked at the patch later this week... Regards, Monty