For what reason should I use a real multi-primary setup?

To be clear, not a multi-writer solution where any node can become the active writer in case of needs, as for Percona XtraDB Cluster (PXC) or Percona Server for MySQL using Group_replication. No, we are talking about a multi-primary setup where I can write at the same time on multiple nodes. I want to insist on this “why?”.

After having excluded the possible solutions mentioned above, both covering the famous 99.995% availability, which is 26.30 minutes of downtime in a year, what is left?

Disaster Recovery? Well, that is something I would love to have, but to be a real DR solution we need to put several kilometers (miles for imperial) in the middle.

And we know …

If you have a New Relic Infrastructure Pro license, and unmonitored MySQL servers, there’s now an easy solution at your fingertips. With the New Relic MySQL integration you can monitor and graph almost any detailed metric you could possibly want. New Relic recently unified its analytics tools with New Relic One, a dashboard that provides quick access to all the New Relic tools. With an Infrastructure Pro subscription, you get access to:

• New Relic Infrastructure: Flexible, dynamic monitoring of your entire infrastructure, from services running in the cloud or on dedicated hosts, to containers running in orchestrated environments.
• New Relic Alerts: A flexible, centralized notification system that unlocks the operational potential of New Relic. Alerts is a single tool to manage alert policies and alert conditions for all of your New Relic data.
…

This post was first published on Oracle MySQL Blog.

If you are running MySQL on premise, it’s maybe the right time to think about migrating your lovely MySQL database somewhere where the MySQL Team prepared a comfortable place for it to stay running and safe.

This awesome place is MySQL Database Service in OCI. For more information about what MDS is and what it provides, please check this blog from my colleague Airton Lastori.

One important word that should come to your mind when we talk about MDS is SECURITY !

Therefore, MDS endpoint can only be a private IP in OCI. This means you won’t be able to expose your MySQL …

During the MDS webinar on how to deploy WordPress on OCI using MDS (slides & video), I briefly explained how to deploy the full architecture on OCI using Resource Manager and Stacks.

The Stack for that architecture is now available on my github: https://github.com/lefred/oci-wordpress-mds/releases/tag/0.0.1

To deploy it, it’s very easy. In OCI’s Dashboard, go on “Resource Manager” and then choose “Stacks“:

Create a new stack and just drop the …

Today we will see how to use MySQL Database Service aka MDS with WordPress.

To achieve this easy task, we will use the architecture we already deployed in this article.

We have then two Compute Instances on OCI, 1 running WordPress (Apache and PHP) and one running MySQL 8.0.

The Plan

This is how we will proceed to migrate to MDS with minimal maintenance time, we will:

1. create a MDS instance
2. verify if the database is ready to act as replication source
3. dump the MySQL instance running on OCI for being migrated to MDS.
4. load the dump in MDS
5. create a user dedicated to the replication
6. create a replication channel on MDS (from OCI to MDS)
7. modify WordPress config to point to MDS

Create a MDS …

In a recent article, I explained how to test MySQL Database Service (aka MDS) on OCI without having to setup a VPN.

A VPN is the recommended way and of course using some man-in-the-middle exposing the MySQL Classic and X Protocol port is something you should absolutely avoid !

So, in this article we will see another way to test or use MDS without VPN but using a more secure option.

SSH

The solution uses a SSH tunnel between your machine (laptop, etc..) and OCI.

How does it work ?

We have a MDS instance (10.0.1.3), and a compute instance (10.0.0.2). The compute instance is in the public subnet and has a public IP assigned to it.

Then we open a SSH tunnel to the compute instance’s public IP that forward all traffic to a certain port on localhost (we will use 3406) …

In a previous blog post on Data Consistency for RDS for MySQL, we presented a workaround to manage run pt-table-checksum on RDS instances. However, if your instance is running a MySQL 8.0.X version, there’s a simpler way to check data consistency.

Starting with 8.0.1, MySQL introduced something called “Dynamic Privileges” which is a solution to grant more granulated privileges to the users, instead of the almighty SUPER privilege.

So what was the issue with pt-table-checksum and RDS again? Since there’s no SUPER privileges for any user, there was no way for the tool to change the binlog_format to STATEMENT… but not anymore.

The solution when using 8.0 is …

Please note that this is not recommended for any production purpose, don’t expose MySQL traffic to the Internet !

MySQL Database Service is now available, take a look at this nice introduction video:

It is usually a very bad idea to expose a database on a public IP (MySQL or any other database ). MDS doesn’t allow you to implement such bad security practice.

The best way to use your MySQL instance is to use a VPN as I explained in this article.

However, this can be restrictive for a simple test. In this post I will illustrate how you can setup a MDS instance and test it without having to setup any kind of VPN. Of course I recommend you to use such practice only for testing …

MySQL for RDS and DBaaS, in general, are very controlled environments by the vendors, meaning that there are missing things like a SUPER grant for the root user (and any user in general). This has some implications on operations, one of them being the impossibility of running pt-table-checksum to verify data consistency between a primary and its replicas.

However, there’s a workaround that might overcome this situation and involves three things:

• The pt-table-checksum itself
• A way to collect executed queries
• And the last one, which can be controversial, is to remove the read-only from the replica and use a maintenance window to stop traffic to the database while pt-table-checksum runs.

The problem with RDS is that you cannot change binlog_format to STATEMENT, which is one of the requirements for pt-table-checksum to run.

The workaround consists of capturing the executed …

You may have noticed, I started to blog also on the official Oracle MySQL Blog.

When I will do so, I will also publish my articles on lefred.be after a short delay.

I really invite you to follow the official Oracle MySQL Blog where you will find information related to MySQL Community but also about our webinars.

Currently, we put the highlight on our great new MySQL Database Service on OCI. My first post, is precisely dedicated to it.