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From:Scott Hess Date:June 28 1999 5:14pm
Subject:Re: to much fragmentation
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That (storing the blobs out to the filesystem) is the solution we're
currently pondering.  The main downside is that the database is being used
as the central "memory" for a system that involves a couple components, and
we'd _really_ rather not teach all components about the off-database blob
storage, if we can get away with it.

Does anyone have firm knowledge of the fragmentation differences between
doing updates and doing a full delete/insert?  I can imagine an
implementation where an update might re-use the currently allocated space,
so if the updated data is larger than the existing data, fragmentation is
going to be a problem.  But a delete followed by an insert may do better.
While we can do some measuring to see if this happens, but I'd like to know
the response of someone with deep knowledge of how MYSQL stores its data.

Thanks,
scott

----- Original Message -----
From: Sasha Pachev <sasha@stripped>
To: David Johnson <davej@stripped>
Cc: <mysql@stripped>
Sent: Saturday, June 26, 1999 3:42 PM
Subject: Re: to much fragmentation


> David Johnson wrote:
> >
> > We have five big tables with blobs in them that get fragmented very
fast.
> > We have to stop out (24 X 7) operation to defrag them too frequently
(one a
> > week).  It seems that the fragmentation happens so fast because MySQL
tries
> > very hard not to waste space.  For instance, we had one table that had
6.75
> > Blocks/Record but only had 1% lost space.
> >
> > We'd love if we could tell  MySQL to use 2Gig for the table and populate
it
> > sparsely, rather than trying
> > so hard to save space.  Is this possible?  Do we need to hack the
source?
> >
> > DJ
> >
> > ---------------------------------------------------------------------
> > Please check "http://www.mysql.com/Manual_chapter/manual_toc.html"
before
> > posting. To request this thread, e-mail mysql-thread5976@stripped
> >
> > To unsubscribe, send a message to the address shown in the
> > List-Unsubscribe header of this message. If you cannot see it,
> > e-mail mysql-unsubscribe@stripped instead.
>
> How about storing the blobs on the filesystem and storing references to
> them in the database? You are not searching through the blobs for
> patterns, are you?
> --
> Sasha Pachev
> http://www.sashanet.com
>
> ---------------------------------------------------------------------
> Please check "http://www.mysql.com/Manual_chapter/manual_toc.html" before
> posting. To request this thread, e-mail mysql-thread5980@stripped
>
> To unsubscribe, send a message to the address shown in the
> List-Unsubscribe header of this message. If you cannot see it,
> e-mail mysql-unsubscribe@stripped instead.
>

Thread
to much fragmentationDavid Johnson26 Jun
  • Re: to much fragmentationSasha Pachev27 Jun
  • Re: to much fragmentationScott Hess28 Jun
    • Re: to much fragmentationVivek Khera28 Jun
    • Re: to much fragmentationMichael Widenius29 Jun
      • Re: to much fragmentationEd Carp29 Jun
        • Re: to much fragmentationSasha Pachev29 Jun
        • Re: to much fragmentationMichael Widenius29 Jun
          • Authentication methodsRoger Smith29 Jun
            • Authentication methodsJani Tolonen1 Jul
        • Re: to much fragmentationScott Hess29 Jun
      • Re: to much fragmentationEd Carp29 Jun
        • Re: to much fragmentationMichael Widenius30 Jun
      • Re: to much fragmentationT├Ánu Samuel29 Jun
  • Re: to much fragmentationScott Hess28 Jun
Re: to much fragmentationFred Lindberg28 Jun