“Hey, what’s going on with my applications? I installed a newer version of MySQL. I have queries that perfectly run with the older version and now I have a lot of errors.”

This is a question some customers have asked me after upgrading MySQL. In this article, we’ll see what one of the most frequent causes of this issue is, and how to solve it.

We are talking about this error:

ERROR 1055 (42000): Expression #2 of SELECT list is not in GROUP BY clause 
and contains nonaggregated column 'test.web_log.user_id' which is not functionally 
dependent on columns in GROUP BY clause; this is incompatible 
with sql_mode=only_full_group_by

Have you ever seen it?

SQL_MODE

As the first thing let me introduce the concept of SQL_MODE.

MySQL can work using different SQL modes that affect the syntax of the queries and validation checks. Based on the configured value of the …

It’s not long now before we’ll be gathering in Austin TX for this year’s Percona Live event. It’s the only conference of its type dedicated entirely to open source databases – of all marques. From a community perspective, we have a few updates to share.

Community Dinner

We’re happy to say that PlanetScale have stepped up to the plate (!) and are sponsoring this year’s community dinner alongside Percona. This year we are taking to the water and consequently numbers are limited to 100 attendees. If you are keen to join us, be sure to not miss the boat.  😉

The speakers’ perspective

For speakers who also enjoy writing, there’s an …

I have recently created a new library called libMariaS3 for a couple of teams at MariaDB which provides a simple C API to Amazon’s S3. This was created because we needed a library which could link to GPLv2 software and Amazon’s own library is Apache 2.0 licensed which is incompatible.

It is not a perfect code base because I had a very short amount of time to get the first release out but it was a very fun project to work on. It led me to take a quick look this morning at a couple of other things I have created in the past to see where they are at today.

libdrizzle-redux

Around 5 years ago I worked for HP’s Advanced Technology Group and I worked on several different Open Source projects during that time. One of those projects was called libAttachSQL which was a …

(In the previous post, Part 2, we covered Initial Data Flushing.)

In this blog post, we continue our series of exploring MyRocks mechanics by looking at the configurable server variables and column family options. In our last post, I explained at a high level how data moves from immutable memtables to disk. In this post, we’re going to talk about what happens to that data as it moves through the compaction process.

What is Compaction?

One of the philosophies of MyRocks is “write the data quickly and sort out data organization later”, which is pretty far removed from engines like InnoDB that take the approach of “continuously organize data on disk so it’s optimal as soon as possible”. MyRocks implements its philosophy in a way that is heavily reliant on a process …

(In the previous post, Part 1, we covered Data Writing.)

In this blog post, we continue on our series of exploring MyRocks mechanics by looking at configurable server variables and column family options. In our last post, I explained at a high level how data first entered memory space and in this post, we’re going to pick up where we left off and talk about how the flush from immutable memtable to disk occurs. We’re also going to talk about how newly created secondary indexes on existing tables get written to disk.

We already know from our previous post in the series that a flush can be prompted by one of several events, the most common of which would be when an active memtable is filled to its maximum capacity and is rotated into immutable status.

When your immutable memtable(s) is ready …

I have written previous blog posts about Oracle Cloud OCI and this series continues. My post titled with Iaas Getting Started was to get us acquainted with important security-focused items like Compartments and network Services like NAT and Internet-Gateways. Then I posted about building MySQL on Compute with Scripting using a mix of OCI Web console navigation… Read More »

I have written previous blog posts about Oracle Cloud OCI and this series continues. My post titled with Iaas Getting Started was to get us acquainted with important security-focused items like Compartments and network Services like NAT and Internet-Gateways. Then I posted about building MySQL on Compute with Scripting using a mix of OCI Web console navigation… Read More »

Continuent Tungsten is one of the few all-in-one solutions for MySQL high availability. In this post I will show you how to automate the upgrade process using Ansible. I will walk you through the individual tasks and, finally, give you the complete playbook.

We will use a rolling approach, upgrading the slaves first, and finally upgrading the former master. There is no need for a master switch, as the process is transparent to the application.

I am assuming you are using the .ini based installation method. If you are still using staging host, I suggest you update your set up.

Pre tasks

The first step is ensuring the cluster is healthy, because we don’t want to start taking nodes offline unless we are sure the cluster is in good shape. One way of doing that is by using the built-in script tungsten_monitor. When we run the playbook, we only need to validate the cluster status on one node, so I am adding …

Mydbops database meetup was held on 26-01-2019 and 48 members from open source database community has attended this event. We had talks on MySQL and MongoDB databases.

Open source database enthusiastic from companies like OLA Cabs, Searce Inc, PayTm, Quikr, Zensar, Grab, SAP labs, Travel Yarri, Meddiff and a few has travelled from other cities of India like Hyderabad and Chennai.

The Welcome talk was given my Selva venkatesh of Mydbops. He spoke about the open source database community and welcomed all the participants and speakers.

Followed by it Karthik P R , CEO/ Founder, Mydbops made his presentation on “InnoDB Performance Optimisation” . InnoDB is the prime engine in MySQL.This talk focuses on the InnoDB Architecture in MySQL 8.0 and its fine tuning. He also answered the various questions raised …

Recently I received several questions about rotating log files for ProxySQL, so I decided to draft it up as a blog post. Let me go by this using an example.

In my testing lab, I have set up a fairly default ProxySQL (version 1.4.13) service. The default location for the proxysql.log is in /var/lib/proxysql.

[root@proxysql ~]# ls -hal /var/lib/proxysql/proxysql.log*
-rw-------. 1 root root 4.9K Jan 30 18:47 /var/lib/proxysql/proxysql.log

I created a pretty basic default logrotate configuration to ensure my logfile rotates on a daily basis and five rotations are kept before expiring.

[root@proxysql ~]# cat /etc/logrotate.d/proxysql
/var/lib/proxysql/proxysql.log {
missingok
daily
notifempty
compress
create 0600 root root
rotate 5
}

First attempt

Let’s check whether this is actually the correct file that is used that we will be rotating. As it turned out it is!

[root@proxysql ~]# lsof | …