Encryption is becoming more and more prevalent and increasingly necessary in today’s world, so I wanted to provide a good overall “getting started” article on using MariaDB’s data at rest encryption (DARE) for anyone out there interested in setting this up in their environment.

MariaDB’s data encryption at rest manual page covers a lot of the specifics, but I wanted to create a quick start guide and also note a few items that might not be immediately obvious.

And due to the number of my examples, I’m splitting this into two posts. The first will focus solely on setting up encryption so you can use it. The second will focus on using it with a number of examples and common use cases.

Also, I feel that I should mention from the outset that, currently, this data at rest encryption only applies to InnoDB/XtraDB tables and Aria …

In my post yesterday, I shared a little known trick for sorting NULLs last when using ORDER BY ASC.

To summarize briefly, NULLs are treated as less than 0 when used in ORDER BY, However, sometimes you do not want that behavior, and you need the NULLs listed last, even though you want your numbers in ascending order.

So a query like the following returns the NULLs first (expected behavior):

SELECT * FROM t1 ORDER BY col1 ASC, col2 ASC;
+--------+------+
| col1   | col2 |
+--------+------+
| apple  | NULL |
| apple  |    5 |
| apple  |   10 |
| banana | NULL |
| banana |    5 |
| banana |   10 |
+--------+------+

The trick I mentioned in my post is to rewrite the query like:

SELECT * FROM t1 ORDER BY col1 ASC, -col2 DESC;

The difference is that we added a minus sign (-) in front of the column …

Take Percona’s blog poll on what database engine you are using to store time series data.

Time series data is some of the most actionable data available when it comes to analyzing trends and making predictions. Simply put, time series data is data that is indexed not just by value, but by time as well – allowing you to view value changes over time as they occur. Obvious uses include the stock market, web traffic, user behavior, etc.

With the increasing number of smart devices in the Internet of Things (IoT), being able to track data over time is more and more important. With time series data, you can measure and make predictions on things like energy consumption, pH values, water consumption, data from environment-aware machines like smart cars, etc. The sensors used in IoT devices and systems generate huge …

Prior to my talk at LaraconEU 2016 I was curious to know how much adoption for MySQL 5.7 was in within the community.

I tweeted this:

Pool, use twitter client to see it:

Which Version of MySQL do you use? SELECT @VERSION; RT for reach, please.

—
Gabriela D'Ávila (@gabidavila) August 23, 2016

Twitter polls only gives you up to 4 items to choose. What I wanted to know is if people were using MariaDB or other forks like Percona, but I didn’t had the proper space, and I  only put three options.

This January I managed to get a bit more syndication on my tweet and more people replied. I added a 4th option, “Other”. This option could …

In this blog post, I’ll look at the types of NVMe flash health information you can get from using the NVMe command line tools.

Checking SATA-based drive health is easy. Whether it’s an SSD or older spinning drive, you can use the

smartctl

 command to get a wealth of information about the device’s performance and health. As an example:

root@blinky:/var/lib/mysql# smartctl -A /dev/sda
smartctl 6.5 2016-01-24 r4214 [x86_64-linux-4.4.0-62-generic] (local build)
Copyright (C) 2002-16, Bruce Allen, Christian Franke, www.smartmontools.org
=== START OF READ SMART DATA SECTION ===
SMART Attributes Data Structure revision number: 16
Vendor Specific SMART Attributes with Thresholds:
ID# ATTRIBUTE_NAME          FLAG     VALUE WORST THRESH TYPE      UPDATED  WHEN_FAILED RAW_VALUE
 1 Raw_Read_Error_Rate     0x002f   100   100   000 …

I was working on a seemingly basic query the other day where the user needed to have an INT column listed in ascending order (i.e., 1, 2, 3, …).

However, the tricky part came in because the column allowed NULLs and the user needed the NULLs to be listed last, not first, which is the default behavior in both MariaDB and MySQL.

We first devised a somewhat convoluted solution where we used ISNULL() first in the ORDER BY, and then the column, but that wasn’t ideal since it added an additional check for each row in the ORDER BY, which we wanted to avoid in a query returning ~5M rows.

To illustrate, a normal query just sorting in ASC order returned:

MariaDB> SELECT * FROM t1 ORDER BY col1 ASC, col3 ASC;
+--------+--------+------+
| col1   | col2   | col3 |
+--------+--------+------+
| apple  | yellow | NULL |
| apple  | red    |    5 |
| apple  | green  |   10 |
| banana | brown  | NULL |
| banana | green  |    5 |
| …

Introduction As previously explained, you can run database integration tests 20 times faster! The trick is to map the data directory in memory, and my previous article showed you what changes you need to do when you have a PostgreSQL or MySQL instance on your machine. In this post, I’m going to expand the original … Continue reading How to run integration tests at warp speed using Docker and tmpfs →

Percona announces the release of Percona Server 5.6.35-80.0 on February 8, 2017. Download the latest version from the Percona web site or the Percona Software Repositories.

Based on MySQL 5.6.35, and including all the bug fixes in it, Percona Server 5.6.35-80.0 is the current GA release in the Percona Server 5.6 series. Percona Server is open-source and free – this is the latest release of our …

As a part database administration, DBA has to take care of sub-components of database like server logs and has to plan for maintenance activity for these components regularly.

MySQL has various types of log i.e binary log, error log, slow query log, general log for different purposes. And after certain time these logs will grow and you will start seeing issues like low disk space, a large number of logs etc.

MySQL allows you to flush logs using flush logs command, next “How to rotate and clean up old MySQL logs? ”

Linux has a utility called “logrotate” , using logrotate we can implement log rotation for MySQL server logs.

Binary logs: This one is critical if you have replication setup, By enabling  expire_logs_days mysql variable you can manage …

This blog we describe an issue with MySQL 5.7’s super_read_only feature when used alongside with GTID in chained slave instances.

Background

In MySQL 5.7.5 and onward introduced the gtid_executed table in the MySQL database to store every GTID. This allows slave instances to use the GTID feature regardless whether the binlog option is set or not. Here is an example of the rows in the gtid_executed table:

mysql> SELECT * FROM mysql.gtid_executed;
+--------------------------------------+----------------+--------------+
| source_uuid                          | interval_start | interval_end | …