Recently, PeterZ pointed a huge difference in memory usage of MySQL 8.0 compare to MySQL 5.7. This can be an issue for small instances if the same configuration for buffers like the buffer pool are not changed.

As explained in Peter’s article, this can lead to the awakening of the so feared OOM Killer !

MorganT, pointed accurately in his comment what is the source of such difference and how this was then caused by the new instrumentation added in MySQL 8.0.

Nothing is free, even as a …

When somebody wants to migrate from a single MySQL instance to a full HA solution using MySQL InnoDB Cluster, the best solution to reduce the downtime is to use asynchronous replication and switch database only once at a certain point in time when everything is ready. This is almost what I explained already in this post.

The most difficult part was related to the provisioning of the existing data to the new cluster members. A backup (physical or logical) was required. It should have been restored on every nodes and we had to be sure to not mess up with the GTIDs.

This is not more the case since MySQL 8.0.17 ! Now we can use the CLONE plugin to start the cluster provisioning too.

The current situation

…

In MySQL 8.0, when using invalid values for date data types, an error is returned. This was not the case in 5.x versions.

Let’s have a look using the table definition of bug 96361:

CREATE TABLE `new_table` (
  `id_table` int(11) NOT NULL AUTO_INCREMENT,
  `text_table` varchar(45) DEFAULT NULL,
  `date_table` date DEFAULT NULL,
  PRIMARY KEY (`id_table`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci

Now we can try the following statement in MySQL 5.7 and MySQL 8.0:

MySQL 5.7.26> SELECT id_table, text_table 
              FROM new_table WHERE date_table = '' OR date_table IS NULL;
Empty set, 1 warning (0.01 sec)

MySQL 5.7.26> show warnings;
+---------+------+-----------------------------------------------------------+
| Level   | Code | Message                                                   | …

You may have noticed that in many of my demos, I disable firewall and SELinux (I even use --initialize-insecure sometimes ). This is just to make things easier… But in fact enabling iptables and SELinux are not complicated.

Firewall

These examples are compatible with Oracle Linux, RedHat and CentOS. If you use another distro, the principle is the same.

For the firewall, we need first to allow incoming traffic to MySQL and MySQL X ports: 3306 and 33060:

# firewall-cmd --zone=public --add-port=3306/tcp --permanent
# firewall-cmd --zone=public --add-port=33060/tcp --permanent

If you don’t plan to restart the firewall, you just need to run the same commands without --permanent to make then immediately active.

Then we need to allow the Group Replication’s communication port. This is usually 33061 but it can be configured in …

You have seen in this previous post, that since 8.0.17, it’s now possible to query the MySQL Router using its REST API.

Additionally, we also saw in this post, that since 8.0.17, we are now able to write extensions to MySQL Shell using the Extension Framework.

Let’s combine both and see how we can integrate the MySQL Router’s REST API in the Shell.

I’ve created an extension in ext.router that creates a MySQL Router Object.

The new extension, as a method to create the object:

This is an example that illustrates how to create a MySQL Router Object, as you can see you can pass the password directly as parameter but it’s not recommended in interactive mode. It’s …

From Drupal’s website, we can see that now the support of MySQL 8 is ready.

I just tested it and it works great !

The only restriction is related to PHP and the support for the new authentication method in php-mysqlnd.

In this previous post, I was happy because it was included in PHP 7.2.8, but this has been reverted back since then. Currently none of the latest version of PHP 7.x is supporting this authentication method.

We can easily verify this, first with the PHP version provided by default in Oracle Linux 8:

# php -i | grep "Loaded plugins\|PHP Version " | tail -n2
PHP Version => 7.2.11
Loaded plugins => mysqlnd,debug_trace,auth_plugin_mysql_native_password, …

I have already posted some time ago a post related to the same topic (see here).

Today, I want to explain the easiest way to create an asynchronous replica from an existing MySQL instance, that this time has already data !

The Existing Situation and the Plan

Currently we have a MySQL server using 8.0.17 and GTID enabled on mysql1. mysql2is a single fresh installed instance without any data.

The plan is to create a replica very quickly and using only a SQL connection.

Preliminary Checks

First we verify that mysql1 has GTID enabled. If not we will enable them:

mysql> select @@server_id,@@gtid_mode,@@enforce_gtid_consistency;
+-------------+-------------+----------------------------+
| @@server_id | @@gtid_mode | @@enforce_gtid_consistency | …

With MySQL Shell 8.0.17, a super cool new feature was released: the MySQL Shell Extensions & Plugins !

You will be able to write your own extensions for the MySQL Shell. You may already saw that I’ve written some modules like Innotop or mydba for MySQL Shell.

However those plugins were written in Python and only accessible in Python mode. With the new Shell Extensions Infrastructure, this is not the case anymore.

Also, this allows you to populate the help automatically.

Extensions are available from the extglobal object.

…

Since MySQL 8.0.16, the Router as the possibility to launch an internal webserver (see Jan’s blog post).

Even if this webserver could serve static files, it was the first piece of a much more interesting solution that is now available since 8.0.17.

It’s possible now to query the MySQL Router via its REST API and get a lot of useful information.

Setup

Let’s first configure our MySQL Router to take advantages of this new feature. In this example, I will add the following lines to /etc/mysqlrouter/mysqlrouter.conf that I created using the --bootsrapcommand line argument:

[http_server]
port=8080

[rest_api]

[rest_router]
require_realm=somerealm

[rest_routing]
require_realm=somerealm …

Create a MySQL InnoDB Cluster using MySQL 8.0 has always been very easy. Certainly thanks to MySQL Shell and server enhancements like SET PERSIST and RESTART statement (see this post).

The most complicated part to deal with was the existing and none existing data. In fact GTID sets must be compatible.

Let me explain that with some examples:

Example 1 – empty servers

If you have empty servers with GTID enabled, manually creating credentials to connect to each MySQL instances will generate GTIDs that will prevent nodes to …