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Webinar Replay and Q&A: High Availability in ProxySQL for HA MySQL infrastructures

Thanks to everyone who participated in our recent webinar on High Availability in ProxySQL and on how to build a solid, scalable and manageable proxy layer using ProxySQL for highly available MySQL infrastructures.

This second joint webinar with ProxySQL creator René Cannaò saw lots of interest and some nice questions from our audience, which we’re sharing below with this blog post as well as the answers to them.

Building a highly available proxy layer creates additional challenges, such as how to manage multiple proxy instances, how to ensure that their configuration is in sync, Virtual IP and fail-over; and more, which we’ve covered in this webinar with René. And we demonstrated how you can make your ProxySQL highly available when deploying it from ClusterControl (download & try it free).

If you missed …

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Handy stored procedure for regular DBA tasks

As a stored procedures fan, I use MySQL stored procedures to get some of my DBA tasks accomplished. To make it simple, I have a template stored procedure that can be customized for several purposes.
The template syntax contains cursor, continue handler, loop, if condition and prepared statement. Thought it may be useful for others – at least, who are searching for the MySQL Stored Procedure syntax – so I’m publishing this post!

Use case: Reorganize tables partition:

In MySQL Cluster, it is required to reorganize all NDB tables’ partitions after adding new data nodes to rebalance the data across all nodes. Also the tables need to be optimized afterwards to reclaim the memory space. For this task I use the following procedure:

DROP PROCEDURE IF EXISTS reorganize_tables;
CREATE PROCEDURE reorganize_tables (IN db_name VARCHAR(50))

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Releasing ProxySQL 1.4.0

Releasing ProxySQL 1.4.0 (beta)

ProxySQL is a high performance, high availability, protocol aware proxy for MySQL, with a GPL license!
Today I am excited to announce the release of ProxySQL 1.4.0, the first beta release of series 1.4.x .
All ProxySQL versions 1.3.x will be mostly bug fixes releases, and unlikely will introduce new features: all the new features will go into ProxySQL 1.4.x .
This also mean that if you are using ProxySQL in production, you should continue using 1.3.x .
Instead, if you are not using ProxySQL in production yet, I strongly recommend trying 1.4.0 and report bugs if you find any.

It can be downloaded here, and freely usable and accessible according to GPL license.
Please report any bugs or feature requests on github …

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Improving the Parallel Applier with Writeset-based Dependency Tracking

MySQL 8.0.1 introduces a new mechanism to track the dependencies between transactions. This feature is used to optimize the binary log applier on asynchronous replication slaves, improving the throughput significantly on workloads where there is low-concurrency on the master and/or on systems with very fast storage.…

Percona XtraDB Cluster Transaction Replay Anomaly

In this blog post, we’ll look at a transaction replay anomaly in Percona XtraDB Cluster.


Percona XtraDB Cluster/Galera replays a transaction if the data is non-conflicting but, the transaction happens to have conflicting locks.


Let’s understand this with an example:

  • Let’s assume a two-node cluster (node-1 and node-2)
  • Base table “t” is created as follows:
create database test;
use test;
create table t (i int, c char(20), primary key pk(i)) engine=innodb;
insert into t values (1, 'abc'), (2, 'abc'), (4, 'abc');
select * from t;
mysql> select * from t;
| i | c |
| 1 | abc |
| 2 | abc |
| 4 | abc |
  • node-2 starts runs a transaction (trx-2):
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BEWARE: Increasing fc_limit can affect SELECT latency

In this blog post, we’ll look at how increasing the fc_limit can affect SELECT latency.


Recent Percona XtraDB Cluster optimizations have exposed fc_limit contention. It was always there, but was never exposed as the Commit Monitor contention was more significant. As it happens with any optimization, once we solve the bigger contention issues, smaller contention issues start popping up. We have seen this pattern in InnoDB, and Percona XtraDB Cluster is no exception. In fact, it is good because it tells us that we are on the right track.

If you haven’t yet checked the performance blogs, then please visit here and …

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Better Than Linear Scaling

In this blog, we’ll look at how to achieve better-than-linear scaling.

Scalability is the capability of a system, network or process to handle a growing amount of work, or its potential to be enlarged to accommodate that growth. For example, we consider a system scalable if it is capable of increasing its total output under an increased load when resources (typically hardware) are added:

It is often accepted as a fact that systems (in particular databases) can’t scale better than linearly. By this I mean when you double resources, the expected performance doubles, at best (and often is less than doubled).  

We can attribute this assumption to Amdahl’s law (, and later …

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MariaDB 10.3.0 Alpha, 5.5.55 Stable, and Connector/J 2.0.0 RC now available

The MariaDB project is pleased to announce the immediate availability of MariaDB 5.5.55 Stable (GA), MariaDB Galera Cluster 5.5.55 Stable (GA) and MariaDB Connector/J 2.0.0 RC. See the release notes and changelogs for details. Download MariaDB 5.5.55 Release Notes Changelog What is MariaDB 5.5? MariaDB APT and YUM Repository Configuration Generator Download MariaDB Galera Cluster […]

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MySQL Challenge

The MySQL team is constantly improving and innovating the product… this time, after having put particular attention to DBAs and operators with Group Replication & InnoDB Cluster,  let’s have a look to what we can also bring to developers.

Let’s start with the following challenge:

Add 5 books from scratch with all their metadata (authors, isbn, edition, year, …) in last than 5 minutes using only MySQL Shell in command line !

Do you thinks this is not possible ? Check the video below:

Amazing isn’t it ?

If you want to learn more about this, please attend Mike Zinner & Alfredo Kojima’s session at Percona Live next week:

Percona Server for MySQL in Docker Swarm with Secrets

This quick post demonstrates using Percona Server for MySQL in Docker Swarm with some new authentication provisioning practices.

Some small changes to the startup script for the Percona-Server container image allows us to specify a file that contains password values to set as our root user’s secret. “Why do we need this functionality,” I hear you cry? When we use an environment variable, it’s not terribly hard to locate the value to which someone has set as their database root password. Environment variables are not well suited for sensitive data. We preach against leaving our important passwords in easy to reach places. So moving towards something more secure whilst retaining usability is desirable. …

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