Emergency

Monthly Archives: March 2008

The tool I’ve been waiting for years

I’ve just been pointed to the nice tool which I was waiting for years to see. It is fincore – little perl script which allows you to see what pages of file are cached in …

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Working with many files and file system fragmentation

Working on performance optimization project (not directly MySQL related) we did a test – creating 100 files writing 4K in the random file for some time and when checking the read speed on the files …

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Researching your MySQL table sizes

I posted a simple INFORMATION_SCHEMA query to find largest tables last month and it got a good response. Today I needed little modifications to that query to look into few more aspects of data sizes …

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MySQL Error Message Nonsenses

What MySQL honestly was never good at is giving good helpful error messages. Start with basics for example – The error message in case of syntax error gives you information about tokens near by but …

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Sharding and Time Base Partitioning

For large number of online applications once you implemented proper sharding you can consider your scaling problems solved – by getting more and more hardware you can grow. As I recently wrote it however does …

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Economics of Performance Optimization

I think every person responsible for Development or Operations of growing application sooner or later have to decide on couple few questions on how to tackle application performance. These questions are: Should we Optimize Application …

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Tradeoff: Insertions versus Point Queries

I’ve been waving my hands about lower bounds. Well, sometimes I haven’t been waving my hands, because the lower bounds are tight. But in other cases (lenient insertions, range queries), the lower bounds are very …

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Speeding up GROUP BY if you want aproximate results

Doing performance analyzes today I wanted to count how many hits come to the pages which get more than couple of visits per day. We had SQL logs in the database so It was pretty …

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Sphinx 0.9.8 reaches RC stage, Docs updated

Andrew Aksenoff is pretty slow with release numbers for Sphinx. By MySQL Users Conference 2007 Sphinx version 0.9.7 was released and today we had just 0.9.8-rc1 announced This minor change in version number corresponds to …

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Evaluating IO subsystem performance for MySQL Needs

I’m often asked how one can evaluate IO subsystem (Hard drive RAID or SAN) performance for MySQL needs so I’ve decided to write some simple steps you can take to get a good feeling about …

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