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From:Michael Widenius Date:January 18 2000 11:05am
Subject:Re: support#318: Advanced Index Tuning + Query Optimization
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Hi!

>>>>> "Joshua" == Joshua Chamas <joshua@stripped> writes:

Joshua> Monty & MySQL hacking team,
Joshua> Hate to answer my own question, but it looks like this might
Joshua> have been recently implemented in 3.23.9, with this note:

Joshua>      Changed optimizer to prefer a range key instead of a ref key when the
> range key can
Joshua>      uses more columns than the ref key (which only can use columns with =).
> For
Joshua>      example, the following type of queries should now be faster: SELECT *
> from
Joshua>      key_part_1=const and key_part_2 > const2

Joshua> Is this right, will this cover my case, where it seems that
Joshua> 'const' keys, like PRIMARY or UNIQUE seem to override other
Joshua> indexes with more & better keys ?

Yes; If h.next_hit is part of your key, the above new optimization may help.

Joshua> Note that I have not tried 3.23.9 yet because there is
Joshua> no WinNT binary version available yet for download, and
Joshua> I am now in pre-production testing on NT, so no more Unix
Joshua> source building for me :(

I hope to have a 3.23.9 ready for testing before tomorrow mid day.
(If not, it has to wait one week before I am back from Tel Aviv).

Anyway, do you think you at some point in the future could try the
queries on Linux?  I would really like to know if the file caching is
as good on NT as on Linux;  According to all my tests it seams that
Linux is 30 % faster when it comes to MySQL, but it would be nice if
someone else also could verify this...

Regards,
Monty
Thread
support#318: Advanced Index Tuning + Query OptimizationJoshua Chamas18 Jan
  • support#318: Advanced Index Tuning + Query OptimizationMichael Widenius18 Jan
  • Re: support#318: Advanced Index Tuning + Query OptimizationJoshua Chamas18 Jan
    • Re: support#318: Advanced Index Tuning + Query OptimizationMichael Widenius18 Jan
  • Re: support#318: Advanced Index Tuning + Query OptimizationJoshua Chamas18 Jan
    • Re: support#318: Advanced Index Tuning + Query OptimizationMichael Widenius18 Jan