I found a couple other articles that discuss the performance differences w/ RC vs RR in InnoDB with very interesting results:

http://serge.frezefond.free.fr/?p=269
https://www.facebook.com/note.php?note_id=244956410932

Hi Nico,

The performance differences between RR and RC is complicated and has less to do with hardware and more to do with internal contention. There are a few things to consider. Internally, READ COMMITTED requires much less in the way of locking and mutexes, so raw transactional throughput should be higher in certain cases. Also, because there is less versioning required in RC, the undo space should see less activity. The undo space is stored on disk, so that could improve I/O performance. However, the flip side of that is that when running in RC mode, only row based replication is supported, which can result in much greater disk activity when writing the binary logs.

Percona did a tpcc benchmark on RC vs RR a couple years ago and found the total transactional throughput to be roughly the same.

Cache all queries which match a schema pattern is one of the few visible feature additions to PECL/mysqlnd_qc 1.1, the client-side query cache plugin for the mysqlnd library. As usual, this client-side cache is mostly transparent, works with all PHP MySQL APIs (mysql, mysqli, PDO_MySQL) and, of course, supports various storage backends including Memcache, process memory, SQLite, user-defined and more. Please, find details in the quickstart.

Setting a cache condition

Caching only selected queries is something that could be done in 1.0 already, for example, using a callback. What’s new is that filtering is built-in to 1.1. The new feature is straigth forward to use.

mysqlnd_qc_set_cache_condition( …

1, Getting locked query from processlist SELECT TIME,USER,HOST,DB,COMMAND,SUBSTR(INFO,1,50) FROM INFORMATION_SCHEMA.PROCESSLIST WHERE STATE='LOCKED' ORDER BY 1 DESC; 2, Getting database schema size from information_schema SELECT TABLE_SCHEMA, SUM((DATA_LENGTH + INDEX_LENGTH) / (1024 * 1024)) AS SIZE_MB FROM INFORMATION_SCHEMA.TABLES GROUP BY TABLE_SCHEMA ORDER BY SIZE_MB DESC 3, Query for bulk drop table statement from database schema SELECT CONCAT('DROP [...]

MySQL Error monitoring script. If you are using MySQL community edition you won’t get any tools to get automatic alerts of any error which has been triggered by MySQL server. For getting those alerts you have to go and check manually in the error file. Here I have created a simple shell script which will [...]

With new blog posts covering newest technologies, discovered bugs and anomalies, this Log Buffer Edition is presented for you. In this Log Buffer #261, you would savor posts from Oracle, SQLServer and MySQL arena. Enjoy Oracle: Oracle ACE Director, Alex Gorbachev makes a quick announcement that Method-R is organizing the online class reunion for the [...]

Do you get write laziness in the command line everything what you need to connect to a MySQL server every time?

It may take less than minute, but sometimes one minute is vital (especially if we’re near the end of the world):

ivancp@ubuntu$ mysql -u root -p -h mysqlhost database

When we are hurry, these commands often fail several times per minute.

The solution: we can create shortcuts with bash alias commands in file ~/.bashrc :

# File ~ /. Bashrc
 
# Command "my" to connect to a local server
alias my='mysql -u root -p'
 
# Command "my2" to connect to a remote server
alias my2='mysql -u root -h 192.168.1.56 -p'

Next time if you want to access the local server just type the command my [database name] , there only ask for database password. You can use any command aliases, I prefer  “my” and “my2” they are short and useful.

But if you have several servers comes …

When people ask me about high availability, I often suggest that it’s helpful to understand whether you’re most interested in service availability, data availability, or both. Of course, you want both – but if cost is an object, you may end up relaxing your requirements. The typical example of an application that needs service availability but doesn’t have strong data availability requirements is something that’s ad-supported. Who cares if the last few comments on funny cat photos are lost?

The OurSQL Podcast did an episode on some of the lesser-known but very useful tools in the Percona Toolkit. pt-show-grants is one of those tools that I use pretty frequently. While the manual page has an explanation of all the features and a few examples, you don’t really see the output, and often you decide whether or not to use a tool based on what it gives you as output.

So here is a small example of an actual command I did today using pt-show-grants. I wanted to find the grants for a particular user. To do that without pt-show-grants, I’d have to login to MySQL, run

mysql> SELECT host FROM mysql.user WHERE user='aus4_dev';

Reading the intro I had a feeling of deja vu!
It’s exactly what happened to me :-) LOL!!! Great blog!