Database talks at OSDC 2014 Gold Coast

Open Query Engineer Daniel Black and Engineer/Trainer Peter Lock will be presenting sessions at the upcoming Open Source Developers’ Conference which is hosted at Griffith University Gold Coast Campus, 4-7 November 2014. Coding for Scale – When One Database Doesn’t Cut it (Daniel) Bigger, Faster, Safer, Easier databases with MariaDB 10 (Peter) MySQL Scale Wars […]

Tracing down a problem, finding sloppy code

Daniel was tracking down what appeared to be a networking problem…. server reported 113 (No route to host) However, an strace did not reveal the networking stack ever returning that. On the other side, IP packets were actually received. When confronted with mysteries like this, I get suspicious – mainly of (fellow) programmers. I suggested a grep […]

Munin graphing of MySQL

While there are many graphing tools out there and we’ve used Munin for a while now. The MySQL plugin for Munin had fallen out of date and the show engine innodb status output changed in 5.5 making some bits of the plugin simply not work any more. Also the show global status has some extra variables so […]

innodb_flush_logs_on_trx_commit and Galera Cluster

We deploy Galera Cluster (in MariaDB) for some clients, and innodb_flush_logs_on_trx_commit is one of the settings we’ve been playing with. The options according to the manual: =0 don’t write or flush at commit, write and flush once per second =1 write and flush at trx commit =2 write log, but only flush once per second The flush […]

Mixing databases usually not optimal

Dan McKinley (Etsy) wrote an [IMHO] insightful article Why MongoDB Never Worked at Etsy. First off, it’s important to realise that it’s not a snipe at MongoDB – it’s a fine tool. The lessons are related to mixing multiple databases in a deployment (administration and monitoring overhead) and the acknowledgement that issues of schema design, […]

Luxbet, MariaDB and Melbourne Cup

Yesterday was Melbourne Cup day in Australia – the biggest annual horse race event in the country, and in the state of Victoria it’s even a public holiday. Open Query does work for Luxbet (part of Tabcorp), and Melbourne Cup day is by far their biggest day of the year in terms of traffic. It’s […]

MySQL Connector/Arduino

Chuck Bell, one of my former colleague from MySQL AB, has created a connector for Arduino to MySQL. So this allows Arduino code to be a direct client of a MySQL or MariaDB server, with Ethernet and WiFi shields supported. With Arduino boards being used more and more, this can come in really handy – not […]

Hint of the day: noatime and relatime in fstab

It’s been written about everywhere, but since we keep spotting installations in the wild where people don’t know about it, it probably deserves another mention. By default, Linux uses the atime option on a disk mount, which means it writes a timestamp (e.g. a write to the drive) every time it reads anything. So in […]

LEVENSHTEIN MySQL stored function

At Open Query we steer clear of code development for clients. We sometimes advise on code, but as a company we don’t want to be in the programmer role. Naturally we do write scripts and other necessities to do our job. Assisting with an Open Source project, I encountered three old UDFs. User Defined Functions […]

MariaDB 5.5 LIMIT ROWS EXAMINED

SELECT … LIMIT has always been very useful, particularly for web applications, restricting the number of rows in the result set to the amount that’s immediately required. To have web apps performing well, it’s always important to only retrieve as many rows as you need and no more. The SQL_CALC_FOUND_ROWS option was added later, so […]