[Phpmyadmin-devel] Innodb and row exact count

[Marc Delisle]

Le 2013-07-27 07:02, Madhura Jayaratne a écrit :
>
>
>
> On Thu, Jul 25, 2013 at 1:39 AM, Marc Delisle <marc at infomarc.info
> <mailto:marc at infomarc.info>> wrote:
>
>     Le 2013-06-12 17:04, Marc Delisle a écrit :
>      > Le 2013-06-12 03:23, Michal Čihař a écrit :
>      >> Hi
>      >>
>      >> Dne Tue, 11 Jun 2013 13:20:44 -0400
>      >> Marc Delisle <marc at infomarc.info <mailto:marc at infomarc.info>>
>     napsal(a):
>      >>
>      >>> I don't find a winning solution so I'm seeking for advice. In
>     this bug
>      >>> report [0], we see that it's annoying to have incorrect page
>     navigation
>      >>> (page selector and arrows) for InnoDB.
>      >>>
>      >>> However, when I apply my proposed patch (which forces an exact
>     count in
>      >>> sql.php), I see delays for larger InnoDB tables.
>      >>>
>      >>> For example, on MySQL 5.5.31, the first time I browse a table
>     having one
>      >>> million rows, I wait for 9 seconds. I tried with 0.5 million
>     and it was
>      >>> about 5 seconds. A few minutes afterwards, even after closing the
>      >>> browser, my big table starts to display in two seconds.
>      >>>
>      >>> I tend to find these delays acceptable and I propose to apply
>     my patch.
>      >>
>      >> I agree this is acceptable and agree with the patch for 4.0.4.
>      >>
>      >> For 4.1 I'd go even further - drop MaxExactCount and use only
>     not exact
>      >> counts on overview pages and count properly when browsing.
>      >
>      > Thanks, I'll have a look at this suggestion for 4.1.
>      >
>      >
>
>     Hmmm, I think we have a problem with exact counting, see
>     https://sourceforge.net/p/phpmyadmin/bugs/4027/
>
>     It's true that 750 M rows is a lot of rows...
>
> Would it make things too slow to get the rough count first and then get
> the exact count if the rough counts is less than some defined threshold?

That's exactly the goal of the MaxExactCount configuration directive, 
and I think it could be applied here as well.

Would not be too slow, as the rough count is very quick.

-- 
Marc Delisle
http://infomarc.info