Announcing Vitess 21 # We're delighted to announce the release of Vitess 21 along with version 2.14.0 of the Vitess Kubernetes Operator. Version 21 focuses on enhancing query compatibility, improving cluster management, and expanding VReplication capabilities, with experimental support for atomic distributed transactions and recursive CTEs. Key features include reference table materialization, multi-metric throttler support, and enhanced Online DDL functionality. Backup and restore processes benefit from a new mysqlshell engine, while vexplain now offers detailed execution traces and schema analysis.

We're delighted to announce the release of Vitess 20 along with version 2.13.0 of the Vitess Kubernetes Operator. Version 20 focuses on usability and maturity of existing features, and continues to build on the solid foundation of scalability and performance established in previous versions. Our commitment remains steadfast in providing a powerful, scalable, and reliable solution for your database scaling needs. What's New in Vitess 20 # Query Compatibility: enhanced DML support including improved query compatibility, Vindex hints, and extended support for various sharded update and delete operations.

As of version 0.2.1, dbdeployer allows users to customize composite sandboxes more than ever. This is done by manipulating the default settings, which are used to deploy the sandbox templates.

In order to appreciate the customization capabilities, let's start with a vanilla deployment, and then we have a look at the possible changes.

$ dbdeployer deploy replication 8.0.4
Installing and starting master
Database installed in $HOME/sandboxes/rsandbox_8_0_4/master
. sandbox server started
Installing and starting slave 1
Database installed in …

MySQL 8.0 will be GA soon (just my assumption: Oracle doesn't tell me anything about its release plans) and it's time to think about having a look at it.
If this is your first try of MySQL 8, get prepared for several impacting differences from previous versions.

In this article I won't tell you what you can do with MySQL 8: there is plenty of material about this, including in this very blog. I will instead concentrate on differences from previous versions that users need to know if they want to avoid surprises.

Data Directory

Let's start with an observation of the data directory.
After a standard installation, without any additional options, I see the following:

Files that I expected to see

auto.cnf
ib_buffer_pool
ib_logfile0
ib_logfile1
ibdata1
ibtmp1
(dir) mysql
(dir) …

Where the hell is it?

The MySQL shell is a potentially useful tool that has been intentionally made difficult to use properly.

It was introduced, with much fanfare, with the MySQL Document Store, as THE tool to bridge the SQL and no-SQL worlds. The release was less than satisfactory, though: MySQL 5.7.12 introduced a new feature (the X-protocol plugin) bundled with the server. The maturity of the plugin was unclear, as it popped out of the unknown into a GA release, without any public testing. It was allegedly GA quality, although the quantity of bug reports that were filed soon after the release proved otherwise. The maturity of the shell was known as "development preview", and so we had a supposedly GA feature that could only be used with an alpha …

In my previous article about roles I said that one of the problems with role usage is that roles need to be activated before they kick in. Let's recap briefly what the problem is:

## new session, as user `root`

mysql [localhost] {root} ((none)) > create role viewer;
Query OK, 0 rows affected (0.01 sec)

mysql [localhost] {root} ((none)) > grant select on *.* to viewer;
Query OK, 0 rows affected (0.01 sec)

mysql [localhost] {root} ((none)) > create user see_it_all identified by 'msandbox';
Query OK, 0 rows affected (0.01 sec)

mysql [localhost] {root} ((none)) > grant viewer to see_it_all;
Query OK, 0 rows affected (0.01 sec)

## NEW session, as user `see_it_all`

mysql [localhost] {see_it_all} ((none)) > use test
ERROR 1044 (42000): Access denied for user 'see_it_all'@'%' to database 'test'

mysql [localhost] {see_it_all} ((none)) > show grants\G …

Overview

MySQL Group Replication was released as GA with MySQL 5.7.17. It is essentially a plugin that, when enabled, allows users to set replication with this new way.

There has been some confusion about the stability and usability of this release. Until recently, MySQL Group Replication (MGR) was only available in the Labs, which traditionally denotes a preview or an use-at-your-own-risk feature. Several months ago we saw the release of Group Replication as a Docker image, which allowed users to deploy a peer-to-peer cluster (every node is a master.) However, about one month after such release, word came from Oracle discouraging this setup, and inviting users to use Group Replicator in …

MySQL-Sandbox installs the MySQL server in isolation, by rejecting existing option files using the option --no-defaults. This is usually a good thing, because you don't want the initialization to be influenced by options in your /etc/my.cnf or other options files in default positions.

However, such isolation is also a problem when you need to add options during the initialization. One example is innodb-page-size, which can be set to many values, but only if the server was initialized accordingly. Thus, you can't set innodb-page-size=64K in your configuration file because the default value is different. It would fail, as InnoDB would conflict.

…

The freshly released MySQL 8.0 includes a data dictionary, which makes MySQL much more reliable. Thanks to this features, we don't have any '.frm' files, and querying the information_schema is 30x to 100x faster than previous versions.

One drawback of the implementation is that the data dictionary tables are hidden by design.

While the reason is fully understandable (they don't want to commit on an interface that may change in the future) many curious users are disappointed, because openness is the basis of good understanding and feedback.

The problem to access the dictionary tables can be split in three parts:

• Finding the list of tables; …

Now that MySQL 8.0 has been revealed, it's time to take a deep look at replication features in the latest releases, and review its overall design.

Server UUID vs Server-ID

At the beginning of replication, there was the server_id variable that identified uniquely a node in a replication system. The variable is still here, but in MySQL 5.6 it was joined by another value, which is created during the server initialisation, regardless of its involvement in a replication system. The server_uuid is a string of hexadecimal characters that is the basis for global transaction identifiers:

select @@server_id, @@server_uuid;
+-------------+--------------------------------------+
| @@server_id | @@server_uuid                        |
+-------------+--------------------------------------+ …