Percona is glad to announce the GA release of Percona XtraBackup 2.4.3 on May 23rd, 2016. Downloads are available from our download site and from apt and yum repositories.

Percona XtraBackup enables MySQL backups without blocking user queries, making it ideal for companies with large data sets and mission-critical applications that cannot tolerate long periods of downtime. Offered …

This year at Etsy, we spun up a “Database Working Group” that talks about all things data. It’s made up of members from many teams: DBA, core development, development tools and data engineering (Hadoop/Vertica). At our last two meetings, we started talking about how many “sources of information” we have in our environment. I hesitate to call them “sources of truth” because in many cases, we just report information to them, not action data based on them. We spent a session whiteboarding all of of these sources and drawing the relationships between them. It was a bit overwhelming to actually visualize the madness.

A few examples:

• We use Chef for configuration management and Chef knows about all database server. It made sense for us to build out our monitoring to generate Nagios configuration based on that data from Chef. When …

Bad query performance is the most common problem DBA’s have to deal with. There are numerous ways to collect, process and analyze the data related to query performance - we’ve covered one of the most popular tools, pt-query-digest, in some of our previous blog posts:

Become a MySQL DBA blog series

• Analyzing your SQL Workload using pt-query-digest
• Deep Dive SQL Workload Analysis using pt-query-digest

When you use ClusterControl though, this is not always needed. You can use the data available in ClusterControl to solve your problem. In this blog post, we’ll look into how ClusterControl can …

Since documentation is not very clear to me on the topic of InnoDB flushing in combination with Linux IO (specifically the write system call), I decided to put together this article in hopes of shedding some light on the matter.

How Linux does I/O

By default, the write() system call returns after all data has been copied from the user space file descriptor into the kernel space buffers. There is no guarantee that data has actually reached the physical storage.

The fsync() call is our friend here. This will block and return only after the data and metadata (e.g. file size, last update time) is completely transferred to the actual physical storage.

There is also fdatasync() which only guarantees the data …

Thu, 2016-05-05 15:33Colin Charles

I'm now in Hanoi, Vietnam, for the launch of OpenCPS. What, might you ask, is OpenCPS? OpenCPS translates to Open Core Public Services, as Vietnam is providing online public services and OpenCPS should sit at its core. Naturally, all of this will be open source, and AGPL licensed. OpenCPS is the first open source project to realize the development of e-government services in Vietnam.

Why does this matter to us? Because at the core of its infrastructure is of course, MariaDB Server as the database of choice, with Red Hat being the Linux provider of choice.

I met the interim project lead, Truong Anh Tuan, quite sometime ago, but the tipping point was a keynote presentation on MariaDB Server at FOSSASIA 2015, in Singapore (so thanks again to the organisers for ensuring I keynoted about MariaDB Server there). So when they approached me at …

What is MetaData Lock?

MySQL uses metadata locking to manage concurrent access to database objects, and to ensure data consistency when performing modifications to the schema: DDL operations. Metadata locking applies not just to tables, but also to schemas and stored programs (procedures, functions, triggers, and scheduled events).

In this post I am going to cover metadata locks on tables and triggers, that are usually seen by DBAs during regular operations/maintenance.

Kindly refer to these 4 different connections to MySQL Instance:

The screenshot shows that the uncommitted transaction may cause metadata lock to ALTER operations. The ALTER will not proceed until the transaction is committed or rolled-back. What is worse, after the ALTER is issued, any queries to that table (even simple SELECT queries) will be blocked. If the ALTER operation is an …

If you remove a file, file system generally just marks in its metadata that previously occupied blocks can now be used for other files – that operation is usually cheap, unless the file has millions of segments (that is such a rare case, only seen in experimental InnoDB features that Oracle thought was a good idea).

This changes a bit with SSDs – if you update underlying device metadata, it can have smarter compaction / grooming / garbage collection underneath. Linux file systems have ‘discard’ option that one should use on top of SSDs – that will extend the life time of their storage quite a bit by TRIM’ing underlying blocks.

Now, each type of storage device will react differently to that, some of them support large TRIM commands, some of them will support high rate of them, some of them won’t, etc – so one has to take that into account when removing files in production environments.

Currently Linux block …

Recently I worked on a feature that involved displaying a list of Folders using an auto-complete field. A simple enough task, but one that had a bit of complexity behind it. For starters, each organization in our system has their own "folder hierarchy", or a tree structure of folders, that could be one to many layers deep. The second thing being that the UI we wanted -- auto-complete -- meant that we would need to "search" through the folders to find a match (based on the user's input) as well as display the path information (where the folder lives) so that the user can differentiate folders if they happen to have the same or similar name. Since it was auto-complete, the searching also needed to be fast or else the user experience would be annoying.

The folder tree structure was stored in a MySQL DB table in a very typical self-referencing schema that represented hierarchical data. Each row of data could have a column that referenced the …

Thu, 2016-04-28 10:03Michaël DeGroot

MariaDB works with many clients to migrate Microsoft SQL and Oracle to MariaDB. With the CONNECT storage engine we can access any ODBC data source in MariaDB. Here's a small HOWTO for those who want to give it a quick try. In this example we use MSSQL, though the same principle should be possible with Oracle ODBC servers.

We start with a clean MariaDB installation, no ODBC drivers installed yet. In this example we used CentOS7. It's important to start at a point where unixODBC is not yet installed, because the Microsoft installation package wants to install its own unixODBC.

Step 1

Microsoft is kind enough to supply us with an ODBC driver for Linux. We download it and unpack it.

Step 2 …

I am one of those crazy people who attempts to write SQL that works on SQlite, MySQL and PostgreSQL. First I should explain why:

This is all for my project sabre/dav. sabre/dav is a server for CalDAV, CardDAV and WebDAV. One of the big design goals is that it this project has to be a library first, and should be easily integratable into existing applications.

To do this effectively, it’s important that it’s largely agnostic to the host platform, and one of the best ways (in my opinion) to achieve that is to have as little dependencies as possible. Adding dependencies such as Doctrine is a great idea for applications or more opinionated frameworks, but for …