Re: Regression test returning different result each time it's run

Hi Øystein,
Thank you for your pointer, that was very helpful.
Hiromichi


--- On Thu, 6/16/11, Øystein Grøvlen <[email protected]> wrote:

> From: Øystein Grøvlen <[email protected]>
> Subject: Re: Regression test returning different result each time it's run
> To: "Hiromichi Watari" <[email protected]>
> Cc: [email protected]
> Date: Thursday, June 16, 2011, 10:32 AM
> On 16/06/2011 16:10, Hiromichi Watari
> wrote:
> > Hi Øystein,
> > Thank you for your reply.
> >
> > I am using the same storage engine (Innob I believe)
> and repeating the test results in different output each
> time.
> 
> Hi,
> 
> By default, InnoDB statistics will vary slightly each time
> you start the 
> server.  Hence, you will get different output. (See my
> blog 
> http://oysteing.blogspot.com/2011/04/more-stable-query-execution-time-by.html
> 
> for a discussion about this.)
> 
> By default, the select test uses the MyISAM storage engine
> which 
> provides exact statistics.
> 
> In order to mask such row count differences, a test can use
> the 
> replace_column command:
> 
> --replace_column 9 x
> explain select ...
> 
> 
> Hope this helps,
> 
> --
> Øystein
> 
> >
> > Hiromichi
> >
> >
> > --- On Thu, 6/16/11, Øystein Grøvlen<[email protected]> 
> wrote:
> >
> >> From: Øystein Grøvlen<[email protected]>
> >> Subject: Re: Regression test returning different
> result each time it's run
> >> To: "Hiromichi Watari"<[email protected]>
> >> Cc: [email protected]
> >> Date: Thursday, June 16, 2011, 3:22 AM
> >> On 15/06/2011 17:08, Hiromichi Watari
> >> wrote:
> >>> Hi,
> >>>
> >>> I'm running a regression test
> >> (/mysql-test/t/select.test) on 5.5 server
> (LaunchPad rev
> >> 3487) but each time I run the test I get different
> number of
> >> rows in explain select statements.
> >>> Is this normal behavior ?  Or am I
> missing
> >> something ?
> >>
> >> The difference is in the estimated number of rows
> in table
> >> t2.  This
> >> number is provided by the storage engine. 
> Maybe you
> >> are using a
> >> different storage engine?
> >>
> >> Hope this helps,
> >>
> >> --
> >> Øystein Grøvlen, Principal Software Engineer
> >> MySQL Group, Oracle
> >> Trondheim, Norway
> >>
> >>>
> >>> Thanks,
> >>> Hiromichi
> >>>
> >>> p.s. I start up the server first then issue
> the
> >> following command,
> >>>
> >>> [hwatari@desktop-intel mysql-test]$ sudo
> >> ./mysql-test-run.pl --extern
> socket=/tmp/mysql.sock
> >> t/select.test
> >>>
> >>>
> >>>
> >>
> -------------------------------------------------------------------------
> >>>
> >>>
> >>> ---
> >>
> /usr/local/mysql-5.5-3487/mysql-test/r/select.result
> >> 2011-05-03 15:00:59.000000000 +0300
> >>> +++
> >>
> /usr/local/mysql-5.5-3487/mysql-test/r/select.reject
> >> 2011-06-15 17:09:43.126761202 +0300
> >>> @@ -133,10 +133,10 @@
> >>>     1
> >> SIMPLE    t2
> >> ref    fld3
> >> fld3    30
> >> const    1    Using where;
> >> Using index
> >>>     explain select fld3
> from t2 ignore
> >> index (fld3) where fld3 = 'honeysuckle';
> >>>     id
> >> select_type    table
> >> type    possible_keys
> >> key    key_len
> >> ref    rows    Extra
> >>> -1    SIMPLE
> >> t2    ALL
> >> NULL    NULL
> >> NULL    NULL
> >> 1199    Using where
> >>> +1    SIMPLE
> >> t2    ALL
> >> NULL    NULL
> >> NULL    NULL
> >> 1209    Using where
> >>>
> >>>
> >>
> >>
> >> --
> >> MySQL Internals Mailing List
> >> For list archives: http://lists.mysql.com/internals
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> >>
> >>
> 
> 
> -- 
> Øystein Grøvlen, Principal Software Engineer
> MySQL Group, Oracle
> Trondheim, Norway
> 

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