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Database

Find Queries That Lack Indexes

December 17, 2014

It’s an ancient tradition amongst MySQL DBAs to analyze slow query log files and sort the results by the so-called “index ratio” to find badly indexed queries. The “index ratio,” in this case, is a heuristic derived from the ratio of rows read to …



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Database

MySQL Error Codes Out Of Context

December 11, 2014

In the wrong context, almost anything can be funny, and MySQL’s error codes are no exception. A few weeks ago, things got a little loopy as we discovered some definitions that could be taken more than one way. How It Began It started with …




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Database

How Exponentially Weighted Moving Averages Work

November 25, 2014

We use exponentially weighted moving averages (EWMAs) quite a bit in a few algorithms. They’re one of the tricks everyone should have in their toolbox for cheaply approximating recent history of a time-series variable. We even wrote an open-source implementation in Go. How do …


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Database

Analyzing Prepared Statement Performance

November 19, 2014

Optimizing MySQL performance requires the ability to inspect production query traffic. If you’re not seeing your application’s production workload, you’re missing a vital part of the picture. In particular, there are lots of performance optimizations your systems might be doing that you’re not aware …