Emergency

Monthly Archives: January 2009

Funniest bug ever

Recently my attention was brought to this bug which is a nightmare bug for any consultant. Working with production systems we assume reads are reads and if we’re just reading we can’t break anything. OK …

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Linux schedulers in tpcc like benchmark

I mentioned earlier that IO scheduler CFQ coming by default in RedHat / CentOS 5.x may be not so good for MySQL. And yesterday one customer reported that just changing cfq to noop solved their …

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iiBench with deletes
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We modified the iiBench benchmark to perform deletions as well as insertions, and compared InnoDB to Tokutek’s Fractal TreeTM storage engine, both running on MySQL 5.1. I’ll post the revised iiBench tarball soon. Here is …

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The perils of InnoDB with Debian and startup scripts

Are you running MySQL on Debian or Ubuntu with InnoDB? You might want to disable /etc/mysql/debian-start. When you run /etc/init.d/mysql start it runs this script, which runs mysqlcheck, which can destroy performance. It can happen …

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Another scalability fix in XtraDB

Recent scalability fixes in InnoDB and also Google’s and your SMP fixes almost made InnoDB results acceptable in primary key lookups queries, but secondary indexes were forgotten for some time. Now having Dell PowerEdge R900 …

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iiBench Fractal Tree Results
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A few weeks ago I reported InnoDB performance on the iiBench 1-billion row insert test. Today I’m reporting on Tokutek’s Fractal TreeTM storage engine performance. We ran iiBench on the same hardware (Sun x4150, 8 …

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5.0.75-build12 Percona binaries

After several important fixes to our patches we made binaries for build12. Fixes include: Control of InnoDB insert buffer to address problems Peter mentioned https://www.percona.com/blog/2009/01/13/some-little-known-facts-about-innodb-insert-buffer/, also check Bug 41811 to see symptoms of problem with …

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Optimizing repeated subexpressions in MySQL

How smart is the MySQL optimizer? If it sees an expression repeated many times, does it realize they’re all the same and not calculate the result for each of them? I had a specific case …

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Beware: ext3 and sync-binlog do not play well together

One of our customers reported strange problem with MySQL having extremely poor performance when sync-binlog=1 is enabled, even though the system with RAID and BBU were expected to have much better performance. The problem could …

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iiBench Contest Results
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At OpenSQL Camp in November we presented a challenge to insert one billion rows, maintaining indexes, into a MySQL table. The best results we have seen are:

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