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From:Michael Widenius Date:January 19 2000 2:34am
Subject:Re: Understanding Transactions...
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Hi!

>>>>> "Patrick" == Patrick Greenwell <patrick@stripped>
> writes:

Patrick> On Tue, 18 Jan 2000, Tim Bunce wrote:
>> Yes there is a time when the update log and database is not perfectly
>> in sync.  In fact that can be quite a long time because delayed writing
>> of the data tables is a valid optimisation that I know Ingres uses
>> and I think Oracle and others do as well. (I did all this RDBMS
>> optimization theory back when I was using Ingres 6.4.)

>> So long as the changes are in the log (and that's sync'd onto the disk)
>> then there's no need to update the tables at once because in the event
>> of a failure the log can be used to 'rollforward' the commited but
>> 'unwritten' changes.

Patrick> This of course is where a lot of performance-suckage can occur though, in 
Patrick> having to commit the transaction to disk. :-(

>> While I'm very happy that MySQL is moving in the direction of
>> supporting transactions I'd caution that it's not something that'll be
>> implemented well in a week or 10 weeks. The complications are manifold.
>> I'm sure you know this already. I hope you can adopt a plan that lets
>> you move forward in small careful steps alongside other developments.

Patrick> Amen. I understand that priorities change when the income source does,
Patrick> however it does seem to be a bit of a radical shift to go from "no
Patrick> transaction support" in the near-midterm future to "transaction support at
Patrick> the TOP of the priority list, above all the things that used to be top
Patrick> priority and that people have been hoping for..." 

Note that most of the transaction stuff is not handled by the the
normal MySQL team;  We will only write a wrapper for the transaction
safe table handler and add update log support to this;  The rest is already
done by our new associates.  In other words;  This shouldn't shift the
table table for other things that much...

We have also recently got more staff;  We have during the last 3
months gone from 5 to 13 persons, so the development speed should
increase a lot as soon as we have got ourselves organized :)

Patrick> In any case, I look very forward to seeing what comes of this as "true"
Patrick> transaction support will most likely aid other developments such as 
Patrick> closer to realtime database replication which is at the top of *my*
Patrick> list... ;-)
 
This thing is at the same priority level as transactions (the highest :).
We are working on both in parallel...

Regards,
Monty
Thread
Understanding Transactions...rjb17 Jan
  • Re: Understanding Transactions...sinisa17 Jan
  • Re: Understanding Transactions...Doug Robinson17 Jan
    • Re: Understanding Transactions...sinisa17 Jan
    • Re: Understanding Transactions...Gregor Welters22 Feb
  • Re: Understanding Transactions...Sasha Pachev17 Jan
    • Re: Understanding Transactions...Tim Bunce17 Jan
      • Re: Understanding Transactions...sinisa18 Jan
        • Re: Understanding Transactions...Tim Bunce18 Jan
          • Re: Understanding Transactions...sinisa18 Jan
            • Re: Understanding Transactions...Tim Bunce18 Jan
              • Re: Understanding Transactions...sinisa18 Jan
                • Re: Understanding Transactions...Tim Bunce18 Jan
                  • Re: Understanding Transactions...sinisa19 Jan
                    • Re: Understanding Transactions...Tim Bunce20 Jan
          • Re: Understanding Transactions...Michael Widenius26 Jan
      • Re: Understanding Transactions...Christopher E. Brown18 Jan
        • Re: Understanding Transactions...James Rogers18 Jan
          • Re: Understanding Transactions...sinisa19 Jan
      • Re: Understanding Transactions...Michael Widenius26 Jan
        • Re: Understanding Transactions...Tim Bunce27 Jan
  • Re: Understanding Transactions...rjb17 Jan
  • Re: Understanding Transactions...Sasha Pachev17 Jan
  • Re: Understanding Transactions...Sven E. van 't Veer18 Jan
    • Re: Understanding Transactions...sinisa18 Jan
      • Re[2]: Understanding Transactions...Sven E. van 't Veer18 Jan
  • Re: Understanding Transactions...Jan Dvorak18 Jan
    • Re: Understanding Transactions...Michael Widenius18 Jan
      • Re: Understanding Transactions...Tim Bunce19 Jan
        • Re: Understanding Transactions...Patrick Greenwell19 Jan
          • Re: Understanding Transactions...sasha19 Jan
            • Re: Understanding Transactions...Patrick Greenwell19 Jan
              • Re: Understanding Transactions...Michael Widenius19 Jan
                • MySQL specific filesystemPatrick Greenwell19 Jan
          • Re: Understanding Transactions...Michael Widenius19 Jan
        • Re: Understanding Transactions...Michael Widenius19 Jan
          • Re: Understanding Transactions...Tim Bunce19 Jan
            • Re: Understanding Transactions...Michael Widenius19 Jan
              • Re: Understanding Transactions...Tim Bunce20 Jan
                • Re: Understanding Transactions...sinisa20 Jan