The “slow query log” is the single most valuable way to examine query execution on your MySQL server. Queries are logged with timing information, and in the case of Percona Server, a great deal of additional performance and other diagnostic information. But the execution time recorded in the log is the time the query took […]
Finding bad queries is a big part of optimization. A scientific optimization process can be simplified to “can anything be improved for less than it costs not to improve it? – if not, we’re done.” In databases, we care most about the work the database is doing. That is, queries. There are other things we […]
Preamble: On performance, workload and scalability: MySQL has always been focused on OLTP workloads. In fact, both Percona Server and MySQL 5.5.7rc have numerous performance improvements which benefit workloads that have high concurrency. Typical OLTP workloads feature numerous clients (perhaps hundreds or thousands) each reading and writing small chunks of data. The recent improvements to […]
This is next post in series Analyzing air traffic performance with InfoBright and MonetDB Air traffic queries in LucidDB Air traffic queries in InfiniDB: early alpha Let me explain the reason of choosing these engines. After initial three posts I am often asked “What is baseline ? Can we compare results with standard MySQL engines […]
For the last couple of months, we’ve been quietly developing a MySQL protocol parser for Maatkit. It isn’t an implementation of the protocol: it’s an observer of the protocol. This lets us gather queries from servers that don’t have a slow query log enabled, at very high time resolution. With this new functionality, it becomes […]
It is a known fact that ext3 is not the most efficient file system out there and for example file removals can be painfully slow and cause a lot of random I/O. However, as it turns out, it can sometimes have a much more severe impact on the MySQL performance that it would seem. When […]
Whilst working with a client recently I noticed a large number of temporary tables being created on disk.
show global status like 'Created_tmp%'
| Created_tmp_disk_tables | 91970 |
| Created_tmp_files | 19624 |
| Created_tmp_tables | 1617031 |
For a couple of months there have been no updates to our msl patch, however recently I managed some time to change this. The functionality was extended a little bit and whatâ€™s even more important the patch is available for all the recent MySQL releases. To remind anyone who has not yet come across this […]
Last week I played with queries from TPC-H benchmarks, particularly comparing MySQL 6.0.4-alpha with 5.1. MySQL 6.0 is interesting here, as there is a lot of new changes in optimizer, which should affect execution plan of TPC-H queries. In reality only two queries (from 22) have significantly better execution time (about them in next posts), […]
Microslow patch is used by many DBAs and developers to accurately time their queries and to catch those which run less than a second as they can also be a performance killer for a busy application. Recently I have started the development of an updated version of the patch. The basic idea is the same […]