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.

PMM (Percona Monitoring and Management) is a great community tool for monitoring your OSDB (MySQL, PostgreSQL, MongoDB) fleet. It’s feature rich, and it’s built and distributed as open-source based on several de-facto industry standard tools such as Grafana and Prometheus. In the second half of last year, major version 2 was released and whereas the major components remained mostly the same, some significant architectural changes were made, but this is out-of-scope for this post.

Upgrading to PMM2 is basically the same as starting from scratch with a fresh install; it requires re-adding all your servers, which can be a painful process if you have a large fleet of instances. For servers where you have OS level access, you can just install the PMM2 agent, but for RDS there is no access to the OS so another approach is required. In this blog, I will focus on getting a large number of RDS instances added.

Adding RDS instances …

Oftentimes, we need to replicate between Amazon Aurora and an external MySQL server. The idea is to start by taking a point-in-time copy of the dataset. Next, we can configure MySQL replication to roll it forward and keep the data up-to-date.

This process is documented by Amazon, however, it relies on the mysqldump method to create the initial copy of the data. If the dataset is in the high GB/TB range, this single-threaded method could take a very long time. Similarly, there are ways to improve the import phase (which can easily take 2x the time of the export).

Let’s explore some tricks to significantly improve the speed of this process.

Preparation Steps

The first step is to enable binary logs in Aurora. Go to the Cluster-level parameter group and make sure binlog_format …

If you are thinking about to move your MySQL databases to the Cloud but you are still reticent, you can maybe use the “Oracle Cloud Free Tier” offer to test it.

Oracle Cloud Free Tier offers you 2 Oracle Autonomous Databases and 2 Oracle Cloud Infrastructure Compute VMs as Always Free services and in addition a 30-day Free Trial with US$300 in free credits.
On these VMs instances (provisioned and managed by Oracle Cloud Infrastructure Compute) you can install your MySQL server. Let’s see how…

Oracle Cloud account creation

Connect to the Oracle Cloud page and fill in your credentials:
…