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From:Michael Widenius Date:March 9 2000 6:14pm
Subject:Re: How MYSQL drives Hard Drive
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>>>>> "Scott" == Scott Hess <scott@stripped> writes:

Scott> On Thu, Mar 09, 2000 at 03:17:06PM +0200, Michael Widenius wrote:
>> Monty wrote:
>> >> How big tables and keys do you have;  isamchk is now that slow and the
>> >> OPTIMIZE TABLE in next MySQL version will be as fast as isamchk.
>> 
>> >>>>> "Scott" == Scott Hess <scott@stripped> writes:
Scott> [In case anyone is paying attention, this is the table I mentioned
Scott> a month or two ago, where it had three integer columns, a timestamp
Scott> column, and a blob column, where the blob columns was _always_ null,
Scott> and no other column was ever null.  I had expected that the table
Scott> would never fragment in that case, but it still seemed to.]
>> 
>> Why do you have the blob column?

Scott> It's a holdover from a time when the blob column was stored in the
Scott> database.  As usage rose, it became clear that the various tables with
Scott> blob columns were causing issues.  We developed a system of storing
Scott> blobs in filesystem files which worked transparently under the
Scott> higher-level parts of the system.  Unfortunately, since we support
Scott> sites with this custom change and sites without, removing the column
Scott> was considered somewhat of a risk.

Can't you just cange the BLOB column to 'CHAR(0)' ?

Scott> In any case, I was quite surprised to find out that the table was
Scott> still fragmenting.  At that point, it was decided to move the entire
Scott> table out of MYSQL, which provided a significant performance
Scott> improvement.

Scott> [Lest anyone take this wrong - we're pushing a lot of data through
Scott> the system, and while we're looking at other database servers, we
Scott> have strong reservations about whether any of them can satisfactorily
Scott> handle our needs.  We're very happy with MYSQL in general, there
Scott> are just relatively tiny edge cases that I'm sniping at, here :-).]

>> By the way, is the table of type ISAM or MyISAM;  You should get
>> much less fragmentation with MyISAM...

Scott> ISAM.  Once 3.23 graduates to a beta release, we'll be testing it on
Scott> our staging machines... but probably not before.

Ok.

Regards,
Monty
Thread
Hardware RAIDPeter Zaitsev1 Mar
  • Re: Hardware RAIDTonu Samuel1 Mar
  • How MYSQL drives Hard DrivePeter Zaitsev2 Mar
    • How MYSQL drives Hard DriveMichael Widenius3 Mar
      • Re: How MYSQL drives Hard DriveScott Hess3 Mar
        • Re: How MYSQL drives Hard Drivesinisa4 Mar
          • Re: How MYSQL drives Hard DriveScott Hess6 Mar
            • Re: How MYSQL drives Hard Drivesinisa6 Mar
        • Re: How MYSQL drives Hard DriveMichael Widenius6 Mar
          • Re: How MYSQL drives Hard DriveScott Hess6 Mar
            • Re: How MYSQL drives Hard DriveMichael Widenius8 Mar
              • Re: How MYSQL drives Hard DriveScott Hess9 Mar
                • Re: How MYSQL drives Hard DriveMichael Widenius9 Mar
                  • Re: How MYSQL drives Hard DriveScott Hess9 Mar
                    • Re: How MYSQL drives Hard DriveMichael Widenius9 Mar
          • Re: How MYSQL drives Hard DrivePeter Zaitsev9 Mar
            • Re: How MYSQL drives Hard DriveMichael Widenius9 Mar
            • Re: How MYSQL drives Hard DriveScott Hess9 Mar
  • Re: How MYSQL drives Hard DrivePeter Zaitsev3 Mar
    • Re: How MYSQL drives Hard DriveMichael Widenius3 Mar
Re: How MYSQL drives Hard DriveEd Carp3 Mar