This blog explains how relay log recovery happens in a scenario where an applier thread (SQL_Thread) is starting for the first time and its starting position is not available for relay log recovery operations. If you are using GTIDs with MASTER_AUTO_POSITION then the following is more or less irrelevant since we then employ a more resilient repositioning scheme. The potential issue described here will also not occur if you have employed crash-safe replication settings, including --sync_master_info=1. With those disclaimers out of the way, let’s proceed.

Background

A crash-safe slave in MySQL …

MySQL 5.6.22 was recently released (it is the latest MySQL 5.6, is GA), and is available for download here.

For this release, there is 1 “Security Note”, 2 “Functionality Changed”, and 5 “Compilation Notes”, all benign, but let me address them:

1. Security Note: The linked OpenSSL library for the MySQL Commercial Server has been updated from version 1.0.1h to version 1.0.1j. Issues fixed in the new version are described at http://www.openssl.org/news/vulnerabilities.html.
2. Functionality Changed: Replication: The variable binlogging_impossible_mode has been renamed binlog_error_action. binlogging_impossible_mode is now deprecated. (Bug #19507567)
3. Functionality Changed: …

MariaDB 5.5.41 was recently released (it is the latest MariaDB 5.5), and is available for download here:

https://downloads.mariadb.org/mariadb/5.5.41/

This is a maintenance release, and so there were not too many changes, *but* please take notice as there are 2 very important bug fixes:

• Bug Fixed: A fix to a serious bug in InnoDB and XtraDB that sometimes could cause a hard lock up of the server (Bug #MDEV-7026)
• Bug Fixed: A fix to unnecessary waits in InnoDB and XtraDB (Bug #MDEV-7100)
• Includes all bugfixes and updates from MySQL 5.5.41 ( …

I showed in an earlier post how to drop a whole database in a very safe way (no replication lag at all) and that technique is usable to drop a single table too, but cleaning up a table can take hours if not days to finish, so this is not the most comfortable way to do that. We also don’t want to have even a small spike of replication lag, so we need to find an another solution.

How to remove database in a safe way
When you have to drop a large database, you’ll encounter some problems, mainly replication…
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What happens when you issue a DROP TABLE command? The table has to be removed from the table dictionary – which is a fast, atomic operation – and has to be removed from file system too. If you use older version than 5.5.10 you have to calculate with a huge amount of time if your buffer pool is big, because the server will scan through the pages there, checking if anything is in memory from that …

MySQL 5.5.41 was recently released (it is the latest MySQL 5.5, is GA), and is available for download here:

http://dev.mysql.com/downloads/mysql/5.5.html

< Forgive me for the flurry of my latest release "Overview and Highlights" that will follow, as I had a serious-at-the-time health issue that delayed me for about a month. Back on track now though. :) >

This release, similar to the last 5.5 release, is mostly uneventful.

There was only 1 “Functionality Added or Changed” bugs this time, and 14 bugs overall fixed.

Out of the 14 bugs, there were 6 InnoDB bugs, and 2 replication bugs, all of which seemed rather minor or obscure. The one worth noting is the “Functionality Added or Changed” item, which was:

• yaSSL was upgraded to version 2.3.5. (Bug #19695101)

With the recent yaSSL issues, …

MySQL 5.6 has an extensive list of new features and changes, so upgrading from a previous version can be risky if not tested extensively. For this reason, we recommend our users to read and understand the changes before doing the upgrade. If you are on older MySQL versions, it is probably time to think about upgrading. MySQL 5.6 was released in February 2013, that’s almost two years ago!

A major upgrade, e.g., from MySQL 5.5 to 5.6 or MariaDB 5.5 to 10, requires the former MySQL/MariaDB server related packages to be uninstalled. In Galera Cluster, there are two ways to upgrade; either by performing offline upgrade (safer, simpler, requires service downtime) or online upgrade (more complex, no downtime). 

In this blog post, we are going to show you how to perform an offline upgrade on Galera-based …

There will be a MySQL & Friends Devroom at the FOSDEM 2015 this year.And surprisingly my talk - not sure you can call 15 min a talk  - had been accepted. (There are other accepted talks of course.) 
It will be a dense talk about Docker/MySQL/Galera :)
We are (at least me) are going to have fun \o/ Erkan
I hope there will be an official announcement too.  

Join 29,000 others and follow Sean Hull on twitter @hullsean. Oh RDS, you offer such promise, but damn it if the devil isn’t always buried in the details. Diving into a recent project, I’ve been looking at upgrading RDS MySQL. Major MySQL upgrades can be a bit messy. Since the entire engine is rebuilt, queries […]

"Should vegetarians open steakhouse restaurants?"

Though someone will probably give me several examples of why they should, I'll argue that they absolutely should not. How can someone who doesn't eat steak convince others to eat at their "steak-only" restaurant?

But this is something a "professional technology benchmarker" (PTB) struggles with on a regular basis. Hello, I'm Tim Callaghan, and I'm a PTB.
professional technology benchmarker, or PTB (noun) : One who compares two technologies as part of their job. One of these technologies is usually the product of the PTB's employer, the other is almost always not. In a past experience I was tasked with comparing the performance of a fully in-memory database with Oracle and MySQL on a "TPC-C like" workload. At the time I was an Oracle expert and working for the in-memory database company, but had never started a single MySQL server in my life. At …

This is yet another story of Django web-framework with time zone support and pain dealing with python datetimes and MySQL on the backend. In other words, offset-naive vs offset-aware datetimes.

Shortly, more about the problem. After reading the official documentation about the time zones, it makes clear that in order to reflect python datetime in the necessary time zone you need to make it tz-aware first and than show in that time zone.

Here is the first issue: tz-aware in what time zone? MySQL stores timestamps in UTC and converts for storage/retrieval from/to the current time zone. By default, the current time zone is the server’s time, can be changed on MySQL globally, per connection etc. So it becomes not obvious what was tz of the value initially before stored in UTC. If you …