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Displaying posts with tag: Open Source (reset)
Un-split brain MySQL via gh-mysql-rewind

We are pleased to release gh-mysql-rewind, a tool that allows us to move MySQL back in time, automatically identify and rewind split brain changes, restoring a split brain server into a healthy replication chain.

I recently had the pleasure of presenting gh-mysql-rewind at FOSDEM. Video and slides are available. Consider following along with the video.


Consider a split brain scenario: a "standard" MySQL replication topology suffered network isolation, and one of the replicas was promoted as new master. Meanwhile, the old master was still receiving …

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Automating Tungsten upgrades using Ansible

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 …

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Summary – Mydbops Database meetup 2

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 …

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Rotating your ProxySQL log files

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 {
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 | …
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Monitoring your 5.7 InnoDB cluster status

Recently we had a customer who came to us for help with monitoring their InnoDB cluster setup. They run a 5.7 InnoDB cluster and suffered from a network outage that split up their cluster leaving it with no writeable primaries. As part of their incident followup, they asked us for methods to monitor this cluster.

I had tested before with InnoDB clusters (in both 8.0 and 5.7 variants) and I was confident that we could parse the cluster node “role” (read-write aka primary vs. read-only aka secondary) from the performance_schema tables. As it turned out, this feature is not in 5.7 but only 8.0. However, the docs on this are wrong for 5.7 as these docs suggest that the performance_schema.group_replication_members table would show PRIMARY and SECONDARY role of each cluster node. I have submitted a …

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What to expect at FOSDEM 2019

In just over two weeks, on Feb 2-3, FOSDEM 2019 will take place. As happens every year, the first weekend of February The University Libre de Bruxelles (ULB) opens the doors of campus Solbosch to the worldwide open source community. What started as a small gathering of open source hackers has now become one of the world’s largest open source community events with speakers from all over the globe. All major open source software vendors want to be there and you will find boots for every possible Linux distribution.

For the third year in a row now, Oracle is organizing a pre-FOSDEM MySQL day. As the name suggests, this event takes place the day before FOSDEM (Friday, Feb 1st). This day is loaded with content on MySQL 8.0. …

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Highly Available Redis Clusters with Automated Sharding Launches at ScaleGrid

PALO ALTO, Calif., January 24, 2019 – ScaleGrid, a rising leader in the Database-as-a-Service (DBaaS) space, has just announced support for Redis Clusters on their fully managed Redis hosting plans. Redis Cluster is the native sharding implementation available within Redis, an open-source in-memory data structure project, that allows you to automatically shard across multiple Redis nodes without having to rely on external tools and utilities.

ScaleGrid is no novice when it comes to deploying and managing complex, sharded clusters in the cloud, as they have provided one of the most powerful sharding tools for their MongoDB hosting solutions since 2013.

With the introduction of Redis Clusters at ScaleGrid, Redis users can now easily create sharded clusters …

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Facebook open-sources new suite of Linux kernel components and tools

An integral part of Facebook’s engineering culture has always been our development work on open source solutions that solve real-world production issues and address key challenges in modern large-scale cloud computing. Today, we are announcing a suite of open source Linux kernel components and related tools that address critical fleet management issues. These include resource control, resource utilization, workload isolation, load balancing, measuring, monitoring, and much more.

Kernel and kernel application developers at Facebook partner with various internal teams to develop technologies that resolve issues and concerns in Facebook’s data centers — the same challenges that many throughout the industry share. The following products are now in production on a massive scale throughout all of Facebook’s infrastructure, as well as at many other organizations.


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Is slave_exec_mode idempotent actually idempotent?

Co-Author: Rafael Alvarez

When you look up the word idempotence in wikipedia you get the following definition: Idempotence is the property of certain operations in mathematics and computer science whereby they can be applied multiple times without changing the result beyond the initial application.

When I think of idempotence in the sense of how IT operations work, the very first thing that comes to mind is Ansible. In Ansible you have a yml file that represents a state you want the target host to be in. For example, I can use the yum module to ensure that MySQL is installed on my RHEL virtual machine. When the playbook is run, it checks if MySQL is installed. If not, it will install it. It is installed, then it will ignore that …

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How to use procedures to increase security in MySQL

MySQL privilege system is small, almost all administrative tasks can be completed using a handful of privileges. If we exclude generic ones as ALL, SHOW DATABASES and USAGE, create and drop permissions as CREATE USER, DROP ROLE or CREATE TABLESPACE, the number of privileges remaining is really limited: PROCESS, PROXY, RELOAD, REPLICATION_CLIENT, REPLICATION_SLAVE, SHUTDOWN and SUPER.

Having such a reduced list of privileges means that it is very difficult to control what a connected session can do. For example, if a user has privileges to stop replication, it also has privileges to start it, and also to configure it. Actually, it has rights to do almost everything as the privilege required to stop replication is …

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