Emergency

Monthly Archives: May 2010

On Good Instrumentation

In so many cases troubleshooting applications I keep thinking how much more efficient things could be going if only there would be a good instrumentation available. Most of applications out there have very little code …

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Percona Welcomes Justin Swanhart

Percona is pleased to officially welcome Justin Swanhart to our team of consultants. Before joining Percona, Justin worked as a MySQL DBA at Gazillion, Yahoo, and Kickfire. Justin has become a regular contributor here on …

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FlashCache: tpcc workload

This is my last post in series on FlashCache testing when the cache is placed on Intel SSD card. This time I am using tpcc-like workload with 1000 Warehouses ( that gives 100GB of data) …

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Disk seeks are evil, so let’s avoid them, pt. 2

In part 1, I discussed why having many disk seeks are bad (they slow down performance), and how fractal tree data structures minimize disk seeks on ad-hoc insertions, whereas B-trees practically guarantee that disk seeks …

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Tuning InnoDB Concurrency Tickets

InnoDB has an oft-unused parameter innodb_concurrency_tickets that seems widely misunderstood. From the docs: “The number of threads that can enter InnoDB concurrently is determined by the innodb_thread_concurrency variable. A thread is placed in a queue …

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Percona Server security fix releases

As you may know MySQL ® announced 5.0.91 and 5.1.47 with serious security fixes, so we provide binary releases of Percona Server 5.0 and Percona Server / XtraDB 5.1 with security patches. Fixed bugs: Bug#53371, …

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Extending Index for Innodb tables can hurt performance in a surprising way

One schema optimization we often do is extending index when there are queries which can use more key part. Typically this is safe operation, unless index length increases dramatically queries which can use index can …

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Disk Seeks are Evil, so Let’s Avoid Them, Part 1

Disk seeks are expensive. Typically, a disk can perform no more than a few hundred seeks per second. So, any database operation that induces a disk seek is going to be slow, perhaps unacceptably slow. …

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Beyond great cache hit ratio

I worked with application recently which has great memcached hit ratio – over 99% but yet still has average page response time over 500ms. Reason ? There are hundreds memcached gets and even though they …

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A workaround for the performance problems of TEMPTABLE views

MySQL supports two different algorithms for views: the MERGE algorithm and the TEMPTABLE algorithm. These two algorithms differ greatly. A view which uses the MERGE algorithm can merge filter conditions into the view query itself. …

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