October 22, 2014

Is your server’s performance about to degrade?

I’ve been talking and writing a bit lately about the scaling problems I’m seeing on fast servers running lots of queries. As a rough guide, I’m seeing this in servers running 20k queries per second and higher, lots of memory, lots of CPU cores, and most queries are running faster than one millisecond; some in […]

Using flow control functions for performance monitoring queries

I’m not big fan on flow control functions like IF or CASE used in MySQL Queries as they are often abused used to create queries which are poorly readable as well as can hardly be optimized well by MySQL Optimizer. One way I find IF statement very useful is computing multiple aggregates over different set […]

MySQL Performance on Memory Appliance

Recently I have had a chance to check out MySQL Performance on “Memory Appliance” by Violin Memory which can be used as extremely high speed storage system. I helped Violin Memory to optimize MySQL for customer workload and Violin memory and also had a chance to do some benchmarks on my own. 2*Quad Core Xeon […]

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 it, it is not perfect but usually can tell you quite a lot of what you should expect from the […]

Can Innodb Read-Ahead reduce read performance ?

I ran into pretty interesting behavior today. We needed to dump and reload large database and we had pretty good IO subsystem so we started number of mysqldump processes in parallel. Unlike in other case when we did load in parallel, dump in parallel did not increase IO rate significantly and we could still see […]

Performance impact of complex queries

What is often underestimated is impact of MySQL Performance by complex queries on large data sets(ie some large aggregate queries) and batch jobs. It is not rare to see queries which were taking milliseconds to stall for few seconds, especially in certain OS configurations, and on low profile servers (ie having only one disk drive) […]

Using LoadAvg for Performance Optimization

Linux and Unixes have excellent metric of system load called “loadavg”. In fact load average is is 3 numbers which correspond to “load average” calculated for one five and 15 minutes. It is computed as exponential moving average so most recent load have more weight in the value than old one. What does Load Average […]

Binary log file size matters (sometimes)

I used to think one should never look at max_binlog_size, however last year I had a couple of interesting cases which showed that sometimes it may be very important variable to tune properly. I meant to write about it earlier but never really had a chance to do it. I have it now!

Innodb transaction history often hides dangerous ‘debt’

In many write-intensive workloads Innodb/XtraDB storage engines you may see hidden and dangerous “debt” being accumulated – unpurged transaction “history” which if not kept in check over time will cause serve performance regression or will take all free space and cause an outage. Let’s talk about where it comes from and what can you do […]

MySQL compression: Compressed and Uncompressed data size

MySQL has information_schema.tables that contain information such as “data_length” or “avg_row_length.” Documentation on this table however is quite poor, making an assumption that those fields are self explanatory – they are not when it comes to tables that employ compression. And this is where inconsistency is born. Lets take a look at the same table […]