In the last quarter of 2021, AWS released Aurora version 3. This new version aligns Aurora with the latest MySQL 8 version, porting many of the advantages MySQL 8 has over previous versions.

While this brings a lot of new interesting features for Aurora, what we are going to cover here is to see how DDLs behave when using the ONLINE option. With a quick comparison with what happens in MySQL 8 standard and with Group Replication.

Tests

All tests were run on an Aurora instance r6g.large with a secondary availability zone. The test was composed of:

        Four connections

• • #1 to perform DDL
  • #2 to perform insert data in the table I am altering
  • #3 to perform insert data on a different table 
  • #4 checking the other node operations

In the Aurora instance, a …

When one is responsible for promoting application development from Dev through the various environments such as QA, UAT, etc., through Production, it is often useful to ensure that configurations in test environments are comparable to the final production environment.  This is especially true with systems where a team of DBAs manage the servers.

Obviously, the difference in performance could be due to differences in hardware, storage, networking, software configuration, etc.  The question is how does one quickly and efficiently find the differences without having to run a lot of different commands and compare the output.  Fortunately, our Percona Toolkit has a couple of utilities that can make this much easier.  When you are tasked with supporting large numbers of servers, efficiency is paramount and this is where the toolkit can really help you!

You can find more information on the Percona Toolkit here: …

Abstract:

By diving into the details of our case study, we will explain how incorrect table statistics may lead the optimizer to choose a suboptimal execution plan. We will also go into how MySQL calculates the table statistics and the ways to correct the table statistics to prevent it from happening again.

Case study: Incorrect table statistics lead the optimizer to choose a poor execution plan.

A customer reported a drastic performance degradation of a query while there were no code changes and no configuration changes made. The data in this article has been edited for brevity and modified to mitigate the exposure of confidential information. The case has also been approved for publication by the customer.

We obtained the query execution plan, and got the results as shown below (execution plan #1):

mysql> explain 
-> SELECT count(con.id)          ,
->        MAX(DAYNAME(con.date)) ,
-> …

Do you wonder if MySQL tells you the truth about writes to tables that have foreign key constraints? The situation is complex, and getting visibility on what is really happening can be a problem.

I found this issue intriguing and decided to share and highlight some examples.

Query Plan

Let us take this example table:

CREATE TABLE `product` (
  `category` int NOT NULL,
  `id` int NOT NULL,
  `price` decimal(10,0) DEFAULT NULL,
  PRIMARY KEY (`category`,`id`)
) ENGINE=InnoDB;

We want to know how costly an example UPDATE against this table will be:

mysql > EXPLAIN update product set id=id+1 where id=65032158 and category=3741760\G
*************************** 1. row ***************************
           id: 1
  select_type: UPDATE
        table: product
   partitions: NULL
         type: range
possible_keys: PRIMARY
          key: PRIMARY
      key_len: 8
          ref: const,const
         rows: 1 …

MySQL Shell For VS Code integrates the MySQL Shell directly into VS Code development workflows and was released last week. This extension to the popular VS Code platform enables interactive editing and execution of SQL for MySQL Databases and optionally the MySQL Database Service for several simultaneous sessions.  It is a preview release and not ready for production but it does have several features that may make the MySQL GUI of choice.

Installation

The installation itself is easy but you will need to download the code from here and not the usual places for MySQL products.  You will, of course, have to have VS Code installed first, and be warned that some of the more tantalizing links for things like documentation are not connected.

MySQL Shell for VS Code installation screen and yes, you will need VS Code installed first.

Usage

The interface is familiar to that of MySQL Workbench but …

The utf8mb4 character set is the new default as of MySQL 8.0, and this change neither affects existing data nor forces any upgrades.

Migration to utf8mb4 has many advantages including:

• It can store more symbols, including emojis
• It has new collations for Asian languages
• It is faster than utf8mb3

Still, you may wonder how migration affects your existing data. This blog covers multiple aspects of it.

Storage Requirements

As the name suggests, the maximum number of bytes that one character can take with character set utf8mb4 is four bytes. This is larger than the requirements for utf8mb3 which takes three bytes and many other MySQL character sets.

Fortunately, utf8mb3 is a subset of …

For a very long part of its history, MySQL replication has been limited in terms of performance. Because there was no way of knowing if transactions or updates were independent, the updates had to be executed on a replica following the exact same sequence of operations as on the primary server. The only way to guarantee the same sequence of operations on the replica was to use a single thread. In this post, we’ll do a dive into the MySQL multi-threaded replication (MTR) implementation and explore the available tuning options.

MTR is the culmination of the evolution in the development of parallel replication which followed the path:

1. Single-threaded replication
2. Per-database replication
3. Logical clock replication

We’ll leave aside, for now, the recent dependency tracking feature.

Context

Before we discuss the multi-threaded implementation, let’s review in …

As part of my ongoing series around MySQL 8 user administration, I’d like to cover one of the new features introduced in MySQL 8.0.27 – multi-factor authentication. In order to establish identity, multi-factor authentication (MFA) is the use of multiple authentication values (factors) during the MySQL authentication process.

Introduction

MFA provides greater security compared to a single-factor authentication method, which has historically been based on simple methods such as password authentication. With MFA, additional authentication methods are enabled, such as requiring multiple passwords, or with devices such as smart cards, security keys, or biometric readers.

As of MySQL 8.0.27, it is now possible to require up to three authentication values to establish identity. In addition to the more common 2FA (two-factor authentication), MySQL can now also support 3FA (three-factor authentication) to complement the …

In keeping with my MySQL 8 user administration and security theme, I’d like to discuss the password verification-required policy introduced in MySQL 8.0.13. With this feature, it is possible to require that attempts to change an account password be verified by specifying the existing current password to be replaced.

Introduction

The password verification-required policy enables DBAs to prevent users from changing a password without proving that they know the current password. When would this happen? Such changes could occur if a user walked away from a terminal session without logging out, and a malicious user uses the open session to change the original user’s MySQL password. As you can imagine, this could have disastrous consequences:

• The original user is now unable to access MySQL until an administrator can reset the account password. 
• The malicious user can access MySQL until a password …

When MySQL client connects to the server it uses one of the authentication plugins. On the server-side, plugins are located in the directory, specified by the option plugin-dir that defaults to

BASEDIR/lib/plugin

  where

BASEDIR

  is the base directory of your MySQL installation. This perfectly works whenever you install MySQL using package manager, or from the Linux tarball.

However, authentication plugins should be also loaded on the client-side. If you installed MySQL into the custom location, you may end up with an error when trying to connect using any plugin requiring a separate client library.

For example, let’s set the …