This blog post is my overview of Group Replication technology.

With Oracle clearly entering the “open source high availability solutions” arena with the release of their brand new Group Replication solution, I believe it is time to review the quality of the first GA (production ready) release.

TL;DR: Having examined the technology, it is my conclusion that Oracle seems to have released the GA version of Group Replication too early. While the product is definitely “working prototype” quality, the release seems rushed and unfinished. I found a significant number of issues, and I would personally not recommend it for production use.

It is obvious that Oracle is trying hard to ship technology to compete with …

In this blog post, we’ll point to a new Docker image for Percona Server for MySQL Group Replication.

Our most recent release of Percona Server for MySQL (Percona Server for MySQL 5.7.17) comes with Group Replication plugins. Unfortunately, since this technology is very new, it requires some fairly complicated steps to setup and get running. To help with that process, I’ve prepare Docker images that simplify its setup procedures.

You can find the image here: https://hub.docker.com/r/perconalab/pgr-57/.

To start the first node (bootstrap the group):

docker run -d -p 3306 --net=clusternet -e …

This edition of Log Buffer covers Oracle, Microsoft SQL Server, and MySQL.

Oracle:

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0001_specify_date_format_mask.md copy

OGG Custom Adapters: How to include a unique identifier for …

Introduction While doing my High-Performance Java Persistence training, I came to realize that it’s worth explaining how a relational database works, as otherwise, it is very difficult to grasp many transaction-related concepts like atomicity, durability, and checkpoints. In this post, I’m going to give a high-level explanation of how a relational database works internally while … Continue reading How does a relational database work →

Whenever we want a query’s results sorted, you may think of using the clause “order by.” You are correct: most of the time, MySQL will return the results in expected order with “order by.”

Be careful, though. Sometimes MySQL may return results in the non-deterministic order even with “order by.”

Indeed, if a query is ordered by a non-unique column, it may return results in an unexpected order. I tested the below example on MySQL 5.1.73, 5.5.54 and 5.6.19 and got the same result. However, when I applied the same example on MySQL 5.7.17, it returned the results in an unexpected order differently.

Follow me step-by-step and see how MySQL returns results in a non-deterministic order. Step 1-4 is for MySQL 5.1.73, 5.5.54 and 5.6.19, Step 5 is for MySQL 5.7.17. After the example, I will explain the reason behind this output.

Step 1. Create the table as …

Updated 2/10/2017

If you've been watching the evolution of database technologies over the past few years, you've seen how quickly JSON has quickly cemented its position in major database servers. Due to its use in the web front-end, JSON has overtaken XML in APIs, and it’s spread through all the layers in the stack one step at a time.

Most major databases supported XML in some fashion for a while, too, but developer uptake wasn’t universal. JSON adoption among developers is nearly universal today, however. (The king is dead, long live the king!) But how good is JSON support in the databases we know and love? We’ll do a comparison in this blog post.

…

Okay, so you’ve read the first post on enabling MariaDB’s data at rest encryption, and now you are ready to create an encrypted table.

And just to get it out of the way for those interested, you can always check your encrypted (and non-encrypted) table stats via:

SELECT * FROM INFORMATION_SCHEMA.INNODB_TABLESPACES_ENCRYPTION;

ENCRYPTION_SCHEME=1 means the table is encrypted and ENCRYPTION_SCHEME=0 means they are not.

But let’s get into some specific examples.

I find the following 4 tables interesting, as the first 3 essentially all create the same table, and the 4th shows how to create a non-encrypted table once you have encryption enabled.

CREATE TABLE t10 (id int) ENGINE=INNODB;
CREATE TABLE t11 (id int) ENGINE=INNODB ENCRYPTED=YES;
CREATE TABLE t12 (id int) ENGINE=INNODB …

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 …