April 18, 2014

Why do we care about MySQL Performance at High Concurrency?

In many MySQL Benchmarks we can see performance compared with rather high level of concurrency. In some cases reaching 4,000 or more concurrent threads which hammer databases as quickly as possible resulting in hundreds or even thousands concurrently active queries. The question is how common is it in production ? The typical metrics to use […]

Is there room for more MySQL IO Optimization?

I prefer to run MySQL with innodb_flush_method=O_DIRECT in most cases – it makes sure there is no overhead of double buffering and I can save the limited amount of file system cache I would normally have on database server for those things which need to be cached — system files, binary log, FRM files, MySQL […]

An update on Percona Live MySQL Conference & Expo 2012

We announced a while back that we were going to continue the traditional MySQL conference in Santa Clara, because O’Reilly wasn’t doing it anymore. But we haven’t given an update in a while. Here’s the current status: We created a conference committee. We created a conference website that allows people to create an account and […]

What’s a good buffer pool read/write ratio?

At Percona Live last week, someone showed me a graph from their Cacti monitoring system, using the templates that I wrote. It was the buffer pool pages read, written, and created. He asked me if the graph was okay. Shouldn’t there be a lot more pages read than written, he asked? It’s a great question. […]

Should we give a MySQL Query Cache a second chance ?

Over last few years I’ve been suggesting more people to disable Query Cache than to enable it. It can cause contention problems as well as stalls and due to coarse invalidation is not as efficient as it could be. These are however mostly due to neglect Query Cache received over almost 10 years, with very […]

MySQL caching methods and tips

“The least expensive query is the query you never run.” Data access is expensive for your application. It often requires CPU, network and disk access, all of which can take a lot of time. Using less computing resources, particularly in the cloud, results in decreased overall operational costs, so caches provide real value by avoiding […]

Cache Miss Storm

I worked on the problem recently which showed itself as rather low MySQL load (probably 5% CPU usage and close to zero IO) would spike to have hundreds instances of threads running at the same time, causing intense utilization spike and server very unresponsive for anywhere from half a minute to ten minutes until everything […]

mk-query-digest, query comments and the query cache

I very much like the fact that MySQL allows you to embed comments into SQL statements. These comments are extremely convenient, because they are written into MySQL log files as part of the query. This includes the general log, the binary log and the slow query log. Maatkit includes tools which interact with these logs, […]

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) on Dell PowerEdge R900 with 32GB of RAM, 22GB allocated for buffer pool and I put 70GB on FlashCache partition […]

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 have some 0.4ms response time they add up to add hundreds of ms to the total response time.