Hi!
On Aug 04, Egor Egorov wrote:
> Sergei Golubchik <[EMAIL PROTECTED]> wrote:
>
> >> We're upgrading from 3.23.58 to 4.0.20 and found that that although the
> >> ALTER test results of sql-bench had been greatly improved, CREATE has
> >> shown nasty performance degradation. Just before needing to make the
> >> decision to revert back to 3.23.58, we found a post here where someone
> >> had a similar problem when using SAN storage. We see the problem using
> >> hardware RAID, shared storage or local SCSI disks.
> >
> > Yes.
> > Since 4.0.17 MySQL sync()'s after it created an .frm file (in
> > CREATE/ALTER TABLE).
>
> And note that the sync() call not only physically writes .frm file to disk, but
> also everything else which is in write cache. If the server is under load, sync()
> call may take seconds, tens of seconds or even hundreds of seconds.
>
> > As one usually doesn't create tables at the huge rate, it is not a
> > problem. Unfortunately, it is apparently a problem for sql-bench :(
>
> Time to add a NO_SYNC option to CREATE TABLE, Sergei ? :)
There is --skip-sync-frm option.
Regards,
Sergei
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/ |/ /_ __/ __/ __ \/ / Sergei Golubchik <[EMAIL PROTECTED]>
/ /|_/ / // /\ \/ /_/ / /__ MySQL AB, Senior Software Developer
/_/ /_/\_, /___/\___\_\___/ Osnabrueck, Germany
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