Few days ago I wrote about testing writing to many files and seeing how this affects sequential read performance. I was very interested to see how it shows itself with real tables so I've got the script and ran tests for MyISAM and Innodb tables on ext3 filesystem. Here is what I found:
The fragmentation we speak in this article is filesystem fragmentation or internal table fragmentation which affects performance of full table scan. Not all queries are going to be affected same way, for example point select reading single page should not be significantly affected - ie you may not be affected as bad as we show here.
Benchmarks were done using this …
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