MySQL INSERT ON DUPLICATE KEY UPDATE is very powerful but often forgotten MySQL feature. It was introduced in MySQL 4.1 but I still constantly see people unaware of it.
Myself I like this feature big deal because it is designed in truly MySQL style – very efficient solution for frequent task while keeping it beautiful […]
Jeremy Cole recently posted very nice post about MySQL Replication Performance. There are however few points I should comment on.
Jeremy Speaks about MyISAM and Innodb in the same terms, in fact they are quite different for Replication. As you probably know MyISAM uses buffered IO so if master crashes you’re out of sync […]
Read moreAs you know MyISAM does not cache data, only indexes. MyISAM assumes OS cache is good enough and uses pread/pwrite system calls for reading/writing datafiles. However OS is not always good in this task, my benchmarks show Linux/Solaris aren’t scalable on intensive pread calls (I believe the same for Windows, but I did not […]
Read moreReturning to post Group commit and real fsync I made several experiments:
I ran sysbench update_key benchmarks without —log-bin, with —log-bin, and with —log-bin and —innodb-support-xa=0 (default value is 1). Results (in transactions / sec)
threads
without —log-bin
—log-bin
—log-bin and
—innodb_support-xa=0
1
1218.68
614.94
1010.44
4
2686.36
667.77
1162.60
16
3993.59
666.14
1161.56
64
3630.55
665.18
1151.36
So we can see group commit is not only broken when XA is enabled but also if XA […]
Read moreEvery so often people ask me the question how should they estimate memory consumption by MySQL Server in given configuration. What is the formula they could use.
The reasons to worry about memory usage are quite understandable. If you configure MySQL Server so it uses too small amount of memory it will likey perform suboptimally. […]
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