July 26, 2014

Why you should ignore MySQL’s key cache hit ratio

I have not caused a fist fight in a while, so it’s time to take off the gloves. I claim that somewhere around of 99% of advice about tuning MySQL’s key cache hit ratio is wrong, even when you hear it from experts. There are two major problems with the key buffer hit ratio, and […]

Virident vCache vs. FlashCache: Part 2

This is the second part in a two-part series comparing Virident’s vCache to FlashCache. The first part was focused on usability and feature comparison; in this post, we’ll look at some sysbench test results. Disclosure: The research and testing conducted for this post were sponsored by Virident. First, some background information. All tests were conducted […]

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 […]

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, […]

MySQL-Memcached or NOSQL Tokyo Tyrant – part 2

Part 1 of our series set-up our “test”  application and looked at boosting performance of the application by buffer MySQL with memcached.  Our test application is simple and requires only 3 basic operations per transaction 2 reads and 1 write.  Using memcached combined with MySQL we ended up nearly getting a 10X performance boost from […]

Maatkit Now Supports Memcached

Have you ever wondered how optimized your Memcached installation is? There is a common misconception that one doesn’t have to think too deeply about Memcached performance, but that is not true. If your setup is inefficient, you could: Burn Memory Waste Network Round-Trips Store Keys That Never Get Retrieved Have a Low Cache Hit Ratio […]

Cache Performance Comparison

Jay Pipes continues cache experiements and has compared performance of MySQL Query Cache and File Cache. Jay uses Apache Benchmark to compare full full stack, cached or not which is realistic but could draw missleading picture as contribution of different components may be different depending on your unique applications. For example for application containing a […]

MySQL Query Cache

MySQL has a great feature called “Query Cache” which is quite helpful for MySQL Performance optimization tasks but there are number of things you need to know. First let me clarify what MySQL Query Cache is – I’ve seen number of people being confused, thinking MySQL Query Cache is the same as Oracle Query Cache […]

What MySQL buffer cache hit rate should you target

“What cache hit rate is good for optimal MySQL Performance” is typical question I’m asked. It could by MyISAM key_buffer or Innodb innodb_buffer_pool it does not really matter. In both cases trying to come up with constant “good” hit rate is looking for trouble. Well of course you can name 100% hit rate and all […]