November 21, 2014

MongoDB Approach to database synchronization

I went to MongoSF today – quite an event, and I hope to have a chance to write more about it. This post is about one replication problem and how MongoDB solves it. If you’re using MySQL Replication when your master goes down it is possible for some writes to be executed on the master, […]

fsyncs on software raid on FusionIO

As soon as we get couple FusionIO cards, there is question how to join them in single space for database. FusionIO does not provide any mirroring/stripping solutions and totally relies on OS tools there. So for Linux we have software RAID and LVM, I tried to followup on my post How many fsync / sec […]

table_cache negative scalability

Couple of months ago there was a post by FreshBooks on getting great performance improvements by lowering table_cache variable. So I decided to investigate what is really happening here. The “common sense” approach to tuning caches is to get them as large as you can if you have enough resources (such as memory). With MySQL […]

SSD, XFS, LVM, fsync, write cache, barrier and lost transactions

We finally managed to get Intel X25-E SSD drive into our lab. I attached it to our Dell PowerEdge R900. The story making it running is worth separate mentioning – along with Intel X25-E I got HighPoint 2300 controller and CentOS 5.2 just could not start with two RAID controllers (Perc/6i and HighPoint 2300). The […]

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 be repeated with SysBench as follows:

Troubleshooting Relay Log Corruption in MySQL

Have you ever seen the replication stopped with message like this: Last_Error: Could not parse relay log event entry. The possible reasons are: the master’s binary log is corrupted (you can check this by running ‘mysqlbinlog’ on the binary log), the slave’s relay log is corrupted (you can check this by running ‘mysqlbinlog’ on the […]

Using MMM to ALTER huge tables

Few months ago, I wrote about a faster way to do certain table modifications online. It works well when all you want is to remove auto_increment or change ENUM values. When it comes to changes that really require table to be rebuilt – adding/dropping columns or indexes, changing data type, converting data to different character […]

Impressions from MongoDB Day London 2014

I visited MongoDB Day in London on November 6. Here are a few observations: App-Developer Centric. It is interesting to see how much MongoDB is about developers; the ops side is something which is a necessary evil developers have to deal with. The ops topics covered in principle that there are no topics about choices […]

Facebook MySQL database engineers ready for Percona Live London 2014

With 1.28 billion active users, Facebook MySQL database engineers are active and extremely valuable contributors to the global MySQL community. So naturally they are also active participants of Percona Live MySQL conferences! And next week’s Percona Live London 2014 (Nov. 3-4) is no exception. (Register now and use the promotional code “Facebook” to save £30!) […]

MySQL 5.6 Full Text Search Throwdown: Webinar Q&A

Yesterday (Oct. 22) I gave a presentation titled “MySQL 5.6 Full Text Search Throwdown.” If you missed it, you can still register to view the recording and my slides. Thanks to everyone who attended, and especially to folks who asked the great questions. I answered as many as we had time for during the session, […]