by Vadim Tkachenko | Feb 2, 2009 | Percona Software
The problem with broken group commit was discusses many times, bug report was reported 3.5Â years ago and still not fixed in MySQLÂ 5.0/5.1 (and most likely will not be in MySQLÂ 5.1). Although the rough truth is this bug is very hard (if possible) to fix properly. In...
by Baron Schwartz | Feb 1, 2009 | Insight for DBAs
One of my favorite MySQL configurations for high availability is master-master replication, which is just like normal master-slave replication except that you can fail over in both directions. Aside from MySQL Cluster, which is more special-purpose, this is probably...
by Peter Zaitsev | Jan 31, 2009 | Percona Events
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 may be we can crash the server with some select query...
by Vadim Tkachenko | Jan 30, 2009 | Benchmarks
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 InnoDB IO problems. I ran tpcc scripts against XtraDB on our Dell PowerEdge...
by kuszmaul | Jan 29, 2009 | MySQL
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 what the performance looks like:...
by Baron Schwartz | Jan 28, 2009 | Insight for DBAs
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 on a server with MyISAM tables, if...
by Vadim Tkachenko | Jan 23, 2009 | Benchmarks, Percona Software
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 on board (16CPU cores, 16GB RAM) I...
by kuszmaul | Jan 23, 2009 | MySQL
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 cores @ 3.16GHz, 16GB memory, 6 SAS disk...
by Vadim Tkachenko | Jan 23, 2009 | Percona Software
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...
by Baron Schwartz | Jan 23, 2009 | Insight for Developers
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 where I needed to find out for sure, so I made a little benchmark. The query...
by Peter Zaitsev | Jan 21, 2009 | Hardware and Storage
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 be repeated with SysBench as follows:...
by kuszmaul | Jan 20, 2009 | MySQL
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: Who Engine Total Time Terminal Rate Notes Mark Callaghan InnoDB 106.2 hours ~1,800 Google PatchesTuned my.cnf...
by Aurimas Mikalauskas | Jan 19, 2009 | Insight for Developers
These days I’m working with a customer who has an application based entirely on stored routines on MySQL side. Even though I haven’t worked much with stored procedures, I though it’s going to be a piece of cake. In the end – it was, but...
by Vadim Tkachenko | Jan 18, 2009 | Benchmarks, Percona Software
Recently I wrote about InnoDB scalability on 24-core box, and we made research of scalability problems in sysbench write workload (benchmark emulates intensive insert/delete queries). By our results the problem is in concurrency on rollback segment, which by default...
by Peter Zaitsev | Jan 15, 2009 | Insight for DBAs
Vadim wrote some time ago about how to find unused indexes with single query. I was working on the system today and found hundreds of unused indexes on dozens of tables so just dropping indexes manually did not look fun. So I extended Vadim’s query to generate...
by Peter Zaitsev | Jan 13, 2009 | Insight for DBAs
Despite being standard Innodb feature forever Insert Buffers remains some kind of mysterious thing for a lot of people, so let me try to explain thing a little bit. Innodb uses insert buffer to “cheat” and not to update index leaf pages when at once but...
by Baron Schwartz | Jan 13, 2009 | Percona Events
As we’ve said before, the Percona team just keeps growing. This time around, I’m pleased to welcome Ryan and Vladimir. Ryan Lowe initially joined us from Florida (USA) in June. In his previous lives he scaled an Alexa top 1000 site with a sharded MySQL...
by Peter Zaitsev | Jan 12, 2009 | Insight for DBAs
There is significant portion of customers which are still using MyISAM when they come to us, so one of the big questions is when it is feasible to move to Innodb and when staying on MyISAM is preferred ? I generally prefer to see Innodb as the main storage engine...
by Baron Schwartz | Jan 9, 2009 | Percona Software
Percona has been building and contributing to open-source software since the company was founded, and individually we’ve been doing the same thing for many years. We think it’s a huge value for our customers and the community. We’re involved in a...
by kuszmaul | Jan 8, 2009 | MySQL
We re-ran iiBench based on Mark Callaghan’s excellent work. We used standard InnoDB engine in MySQL 5.1 without the Google or Percona patches. Our hardware is similar to Mark’s except we used a 6-disk hardware RAID 0, whereas Mark employed a 10-disk...
