On May 19, 2009, at 11:07 AM, Marc Alff wrote:
>
> Hi Guilhem
>
> Guilhem Bichot wrote:
>> Hello Marc,
>>
>> I see that for files, object_instance_begin is always 0 in my tests:
>>
>> mysql> select * from EVENTS_WAITS_SUMMARY_BY_INSTANCE where
>> object_instance_begin=0 order by 1 ;
>> +---------------------------------------------
>> +-----------------------+------------+----------------
>> +----------------+----------------+----------------+
>>
>> | EVENT_NAME |
>> OBJECT_INSTANCE_BEGIN |
>> COUNT_STAR | SUM_TIMER_WAIT | MIN_TIMER_WAIT | AVG_TIMER_WAIT |
>> MAX_TIMER_WAIT |
>> +---------------------------------------------
>> +-----------------------+------------+----------------
>> +----------------+----------------+----------------+
>>
>> | wait/io/file/maria/control |
>> 0 |
>> 6 | 113417304 | 1987986 | 18902884 |
>> 62948886 |
>> | wait/io/file/maria/log_descriptor_directory |
>> 0 |
>> 2 | 85008924 | 5579574 | 42504462 |
>> 79429350 |
>> | wait/io/file/maria/recovery_trace |
>> 0 |
>> 7 | 182696514 | 780780 | 26099502 |
>> 60282222 |
>> | wait/io/file/myisam/dfile |
>> 0 |
>> 1 | 12882870 | 12882870 | 12882870 |
>> 12882870 |
>> | wait/io/file/myisam/dfile |
>> 0 |
>> 1 | 12924912 | 12924912 | 12924912 |
>> 12924912 |
>> | wait/io/file/myisam/dfile |
>> 0 |
>> 4 | 24180156 | 1285284 | 6045039 |
>> 13159146 |
>> | wait/io/file/myisam/dfile |
>> 0 |
>> 3 | 17951934 | 1327326 | 5983978 |
>> 13975962 |
>>
>> As this is a "by_instance" table (one line per MyISAM data file, the
>> dfile lines above), I expected a discriminating information to be
>> present, so that I can know, among the 3 dfile above, which one
>> belongs
>> to what; for this, I expected file names to show up.
>> I see that for mutex instances, the column is not 0.
>
> object_instance_begin is only an address, it can not be a file name.
>
> For files, there is no "identity" pointer that can be used, since
> there
> is no file object the code can use (FILE* is a file handle, not
> representative of the underlying file itself).
>
> So, I used the address of the PFS_FILE* structure itself for:
> - EVENTS_WAITS_CURRENT.OBJECT_INSTANCE_BEGIN
> - EVENTS_WAITS_HISTORY.OBJECT_INSTANCE_BEGIN
> - EVENTS_WAITS_HISTORY_LONG.OBJECT_INSTANCE_BEGIN
> - EVENTS_WAITS_SUMMARY_BY_INSTANCE.OBJECT_INSTANCE_BEGIN
>
> so that there is always a discriminant in OBJECT_INSTANCE_BEGIN,
> globally unique
Does the PFS_FILE* structure have any meaning for users, or is the only
relevant thing about it that different values indicate different files?
> Now, this raise the question about adding an OBJECT_INSTANCE_BEGIN
> column in FILE_INSTANCES, so that we have both the file name and
> address, to join data ...
My next question was going to be, is there any way to associate a given
OBJECT_INSTANCE_BEGIN value with a file name? I take it the answer is
"no."
> The same question will arise for tables, where a table can be named:
> - either by schema + name
> - or by object_instance_begin (the address of the table share),
>
> when we get to something like TABLE_INSTANCES, and summary by tables.
>
> Peter, any opinion ?
>
>
>
>
> --
> MySQL Code Commits Mailing List
> For list archives: http://lists.mysql.com/commits
> To unsubscribe: http://lists.mysql.com/commits?unsub=1
>
--
Paul DuBois
Sun Microsystems / MySQL Documentation Team
Madison, Wisconsin, USA
www.mysql.com
