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


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?



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create indexes descending
April 11, 2011 03:55PM
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