The latest from the MySQL community

The idea of ACID transactions are a basic feature of SQL’s individual Data Manipulation Language (DML) commands, like the INSERT, UPDATE, and DELETE statements. Transactions across two or more tables are a natural extension of ACID compliance features provided by DML commands. However, they require a structured programming approach, like a store procedure or like API implemented in an imperative language.

Surprisingly, transaction management wasn’t covered well in Alan Beaulieu’s Learning SQL because he only provided pseudo code logic. While I thought troubleshoot some broken MySQL SQL/PSM logic would be a good learning experience for students, it wasn’t. So, I wrote this sample code to show how to achieve an all or nothing transaction across four tables.

The code for this example on transaction management lets you perform the important tasks necessary to effect transaction …

A question has cropped up recently: how does one install Galera Cluster 4 with MySQL 8 on Ubuntu 20.04 LTS (Focal Fossa)? This quick guide will get you started.

Install 3 Galera Cluster nodes with the base OS being Ubuntu 20.04. Remember to run apt update and apt upgrade.

Once this is done, edit: /etc/apt/sources.list.d/galera.list and add the following lines:

deb https://releases.galeracluster.com/galera-4/ubuntu focal main
deb https://releases.galeracluster.com/mysql-wsrep-8.0/ubuntu focal main

Once that is done, don’t forget to also pin the preference to the Galera Cluster repository. To do this, edit: /etc/apt/preferences.d/galera.pref and have it read:

# Prefer the Codership repository
Package: *
Pin: origin releases.galeracluster.com
Pin-Priority: 1001

Once you are done, run apt update yet again. Now you are ready to install Galera Cluster 4 with MySQL 8, just by …

Recently one of our customers ran into an issue, wherein a bad actor(code) from the application had made the wrong update to 16 M records of a critical table in the database, causing the entire production process to go down. The application Team was able to find the bad actor and block it, our Remote DBA was involved in the Data Recovery/Rollback.

Here I would like to discuss possible recovery methods for the above said scenario

Delayed Slave:

A simple and effective way to recover is by using a delayed slave, RDS started supporting this feature from version 5.6.40 and 5.7.22 i.e., you can induce a SQL thread delay-interval for applying the writes to a slave, detailed implementation is covered in our blog here. It’s …

»If at all possible, we build databases so that the working set of the database fits into memory.« What does that even mean?

Working Set

In computer science, the “Working Set” of a program is the set of things it will be accessing in the near future. Because computer science has not yet solved looking into the future, we are looking at the set of things we accessed most recently and hope for The Best™.

The Best™ here being that our future access pattern is very similar to our most recent past access pattern.

Why Memory Matters

In MySQL, the “things we access” in the Working Set definition is RAM, Memory.

We do care, because memory is fast. How fast is fast?

Images from …

This brief summarises the proceedings and outcomes of the 2nd MyWebinar which was held on 13th February 2021 at Online Webinar. As part of our thought leadership webinar series, our latest hosting webinar Migrate your EOL MySQL Servers (seamless migration to MySQL group replication / InnoDB cluster)

We have conducted MyWebinar with a very positive response with the help of software like zoom hosting arrangement and YouTube streaming and commitment of our business team, We have easily planned the perfect broadcasting for all of the attendees.

Over 30+ people took part in our webinar on 13th Feb 2021, to learn MySQL EOL and upgrade path. The session “Migrate your EOL MySQL servers to HA Complaint GR Cluster / InnoDB Cluster With Zero Downtime” by  …

Hey, dolphins! Ready to test your NDB backup and restore skills?

Q1: You have a large database which takes 3 hours to back up. Insert/update/delete traffic will run during the backup. How do you run a backup so that none of the inserts/updates/deletes which are executed after the start of the backup are reflected in the backup files?…

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This week I was evaluating AWS QLDB. Specifically the verifiable history of changes to determine how to simplify present processes that perform auditing via CDC. This is not the first time I have looked at QLDB so there was nothing that new to learn.

What I found was that creating a workable solution with an existing application is hard. Even harder is creating an example to publish in this blog (and the purpose of this post).

First some background.

Using MySQL as the source of information, how can you leverage QLDB? It’s easy to stream data from MySQL Aurora, and it’s easy to stream data from QLDB, but it not that easy to place real-time data into QLDB. AWS DMS is a good way to move data from a source to a target, previously my work has included MySQL to MySQL, MySQL to Redshift, and MySQL to Kinesis, …

Author Andriy Lysyuk.

Introduction

In the previous post, we described a situation when the UnDrop For InnoDB toolkit can be used to recover an accidentally dropped table with innodb_file_per_table=OFF.
In this post, we’ll show how to recover MySQL tables or databases if innodb_file_per_table is ON. This option tells InnoDB to store each table with a user in a separate data file.

For the recovery test, we’ll use the same sakila database that we used in the previous post.

root@test:/var/lib/mysql/sakila# ls …

Author Andriy Lysyuk.

Introduction

Unfortunately, human mistakes are inevitable. That’s how life is. Wrong DROP DATABASE or DROP TABLE may destroy critical data on the MySQL server. Obviously, backups would help, however they’re not always available. This situation is frightening but not hopeless. In many cases it’s possible to recover almost all the data that was in the database or table.
Let’s look at how we can do it. The recovery plan depends on whether InnoDB kept all data in a single ibdata1 or each table had its own tablespace. In this post we will consider the case when innodb_file_per_table=OFF. This option assumes that all tables are stored in a common file, usually located at /var/lib/mysql/ibdata1.

One Wrong Move, And The Table’s Gone

For our scenario, we use …

Most modern websites and applications ground on data collection, storage, and analysis. Databases take an active part in building the entire Web environment. That’s why it is crucial to ensure correct data retrieval from databases and appropriate ways of data manipulation. To modify your data properly, you will need to execute SQL queries. The current […]

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