maria-developers team mailing list archive

[Michael Widenius <monty@xxxxxxxxxxxx>]

Hi!

>>>>> "MARK" == MARK CALLAGHAN <mdcallag@xxxxxxxxx> 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@xxxxxxxxx> 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