Presentation of some of the new features of MySQL 8.0.16 released on April 25, 2019

Recently, I received a support request where the customer wanted to convert an INTEGER column to BIGINT on two tables. These tables are related by a foreign key, and it is a 3 node PXC cluster. These tables are 20GB and 82 GB in size and DDL’s on such tables in a production environment is always a challenge. We have options like direct ALTER or using pt-online-schema-change to get this done, but this is a very special case where none of them will be able to do this DDL. To demonstrate why this is so, please follow the table schema and the example below about DDL queries on foreign key columns. In the end, I will discuss an easy workaround, too.

Please take a look at table schema before reading further. In the below schema, the product_catalog_id column from the product_details table refers to catalog_id column from the product_catalog table. Both these fields are INT(11) …

(In the previous post, Part 6, we covered Replication.)

In this final blog post, we conclude our series of exploring MyRocks by taking a look at use case considerations. After all, having knowledge of how an engine works is really only applicable if you feel like you’re in a good position to use it.

Advantages of MyRocks

Let’s start by talking about some of the advantages of MyRocks.

Compression

MyRocks will typically do a good job of reducing the physical footprint of your data. As I mentioned in my previous post in this series about compression, you have the ability to configure compression down to the individual compaction layers for each column family. You also get the advantage of the fact that data isn’t updated once it’s written to disk. Compaction, which was …

So the issue of max_connections dropping from the value set in your my.cnf file down to 214 has been around for a little while on Ubuntu.

As an example, it was noted here back in 2015

• https://codepoets.co.uk/2015/mysql-max_connections-stuck-on-214/

I ran into this again recently and was resolved with the following steps.


# cp /lib/systemd/system/mysql.service /etc/systemd/system/
# cd /etc/systemd/system/
# vi mysql.service

LimitNOFILE=infinity
LimitMEMLOCK=infinity

# systemctl daemon-reload
# systemctl restart mysql


Once those steps completed the MySQL connections were stable at the given parameter in the my.cnf file. 

Just a reminder for the shows hold this week where you can find either MySQL Community team or MySQL experts at. Please find them below:

• DevTalks Romania, Bucharest, Romania, Jun 6-7, 2019

  • Do not miss two MySQL talks, both given by Georgi Kodinov, the Team Lead, MySQL Server General Team on:
    • "What's New in MySQL 8.0 Security" 
    • "MySQL Enterprise Data Masking" 
  • Do not miss to stop by at our MySQL + Bronto booth to talk to both teams!
• BGOUG, Pravets, Bulgaria, Jun 7-9, 2019
  • We are Partner of BGOUG this year again. Do not miss the MySQL talk on "MySQL InnoDB …

The annual MySQL Community Awards were held in Austin, Texas at Percona Live on Wednesday May 29, 2019 during the lunchtime keynotes. The MySQL Community Awards initiative is an effort to acknowledge and thank individuals and corporations for their contributions to the MySQL ecosystem. The nominations for the awards come from the community itself.  It is a from-the-community, by-the-community, and for-the-community effort. There is no corporate involvement. Awards are given in the following three categories: Community Contributor (a person), Application (an application / project), and Corporate Contributor (a company). The committee is composed of an independent group of community members of different orientation and opinion, themselves past winners or known contributors to the community. These awards are not to be confused with the ones …

Here are my slides about MySQL 8.0 Scalability & Benchmarks from Percona LIVE 2019 in Austin, TX. (and I also realized I forgot to publish my slides from MySQL pre-FOSDEM 2019 Day about MySQL Performance Tuning, so fixing it now ;-))

• MySQL 8.0 Benchmarks [PDF]
• MySQL 8.0 Performance Tuning [PDF]

P.S. Percona LIVE was "just awesome" ! ;-))

Rgds,
-Dimitri

Redhat Enterprise Linux 8 packages have been released into our repositories.  Recent versions of Percona Server for MySQL, Percona XtraDB Cluster, Percona XtraBackup,  Percona Server for MongoDB, Percona Toolkit, and the PMM Client can now be automatically installed via Redhats dnf utility.

How to install RHEL 8

Visit https://www.redhat.com/en/technologies/linux-platforms/enterprise-linux and follow the instructions.  If you have a paid subscription,  you will be able to download the RHEL 8 DVD ISO and use this to install the operating system on a physical or virtual machine.   You may also signup for a free 30-day trial.

Once installed, you will need to register the instance with Redhat using subscription-manager in order to update your instance.   While logged in …

Ok, so if you’re reading this, then I can guess you’ve got a MySQL InnoDB Cluster in an awkard shape, i.e. you need to restore a backup and add the instance back into the cluster, so we have all our instances again.

As it might be logical to think “ah, but I’ve only lost 1 instance, a read-only instance, so all I have to do is backup & restore the other read-only instance and I’m home free. Well I want to make it a little harder. So in this scenario, assume that we’ve lost both the READ-ONLY instances, so I need to backup my primary READ-WRITE instance.

I’ve got a 8.0.16 instance, on Oracle Linux 7.4. We’ll be looking at 2 hosts, ic1 & ic3.

We’ll be using the MySQL Enterprise Edition Server, that bundles MySQL Enterprise Backup with the rpm’s so we don’t need to install anything else.

I’ll assume you’ve got access to Oracle …

MySQL 8.0 upgrade checklist

Recently one of our customers in Fintech. business (among the largest one in the Asia) wanted to upgrade from MySQL 5.7 to MySQL. 8.0. and they approached us for a safest and durable MySQL upgrade strategy, roadmap and execution. In Fintech. business every transaction needs to durable from statutory regulatory compliance perspective and we at MinervaDB never wanted to go for unplanned / easy in-place MySQL 8.0 upgrade method here without proper pre-migration audit, We wanted to list down in detail what are the possible scenarios this MySQL 8.0 upgrade will fail and the compatibility issues between MySQL 5.7 and MySQL 8.0. Thankfully Upgrade Checker utility that comes with MySQL Shell 8.0 can be executed against MySQL 5.7 server to confirm upgrade readiness, We have written a blog on MySQL Shell 8.0 Upgrade Checker …