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create indexes descending
Posted by: Dave Edwards ()
Date: April 11, 2011 03:55PM

Hi

MySQL 5.01 on Debian Squeeze

Been doing some testing with a large table of data (20 million rows) on indexing.
It is real data and one of the queries checks to see how many entries between a date span (from 1 minute to 30 minutes). For years this has been fast but it has been getting slower. I used to be able to easily query 250+ entries per second but now it is much lower and the only difference is the number of rows. Now this is where the order index descending would be useful. 99.9 percent of queries are in the last day so an index (on date) descending search would be tiny an very fast in most cases. Interestingly I have tested this in SQL Server and the performance is slower on a small recordset but the dropoff is minimal with the index set to descending and it easily outperforms MySQL on a lesser machine spec with the big dataset (~55 more queries per second).

My questions are:
Does MySQL already have the ability to create descending indexes and I have missed it?
If descending indexes are not yet available when will they be?

Regards

Dave

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Subject Views Written By Posted
create indexes descending 2947 Dave Edwards 04/11/2011 03:55PM
Re: create indexes descending 720 Shane Bester 04/24/2011 05:43AM
Re: create indexes descending 641 Dave Edwards 04/24/2011 09:40AM
Re: create indexes descending 611 Stephen Jackson 05/04/2011 02:11PM
Re: create indexes descending 601 Dave Edwards 05/04/2011 03:15PM
Re: create indexes descending 758 Yos Dwiatmojo 05/11/2011 08:32PM
Re: create indexes descending 631 Dave Edwards 05/12/2011 12:34AM
Re: create indexes descending 583 Shane Bester 05/12/2011 12:40AM


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