I once found a slowlog called simply "1". But I did not track down the cause. Possibly it was a not-so-correct configuration script.
SHOW VARIABLES LIKE '%dir%';
ibdata1 grows (never shrinks) when data is added, ALTER is done, etc. It will reuse free space within itself.
innodb_file_per_table=1 is recommended
Having an explicit PRIMARY KEY on InnoDB tables is recommended. (MEMORY did not care much.)
> -----Original Message-----
> From: Larry Martell [mailto:larry.martell@stripped]
> Sent: Wednesday, July 03, 2013 9:29 AM
> To: shawn green
> Cc: mysql@stripped
> Subject: Re: 1 file
> On Wed, Jul 3, 2013 at 9:51 AM, shawn green <shawn.l.green@stripped>
> > Hello Larry,
> > On 7/3/2013 11:27 AM, Larry Martell wrote:
> >> We recently changed from in memory files to InnoDB files. Today we
> >> noticed that in every server's data dir there is file called '1' that
> >> seems to get updated every time the iddata1 file gets updated. On
> >> some servers it's comparable in size to the iddata1 file, on other
> >> servers it's 10-15x larger, and on others it's 1/2 the size. What is
> >> this file. Googling revealed nothing about this.
> > That is not something an official MySQL build would do. Consult with
> > the person (or group) that compiled your binaries.
> > Now, if you have enabled --innodb-file-per-table and if you have named
> > your table '1' then that file is probably '1.ibd'. That would be
> > expected. But that seems unlikely based on your other details.
> > Did you also enable a separate undo log, perhaps? Although if you had,
> > it should be 'undo1' not just '1'
> > http://dev.mysql.com/doc/refman/5.6/en/innodb-parameters.html#sysvar_i
> > nnodb_undo_tablespaces
> > So, that simple '1' file also seems unusual to me.
> Thanks for the reply.
> I asked our DBA group and here's the answer I got:
> The file is currently accessed by mysqld, please don’t delete it.
> Looking at the file header, it appeared to be an innodb datafile.
> But no idea how it was created.
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