Distributed systems are hard – I just want to echo that. In MySQL, we have quite a number of options to run highly available systems. However, real fault tolerant systems are difficult to achieve.

Take for example a common use case of multi-DC replication where Orchestrator is responsible for managing the topology, while ProxySQL takes care of the routing/proxying to the correct server, as illustrated below. A rare case you might encounter is that the primary MySQL

node01

on DC1 might have a blip of a couple of seconds. Because Orchestrator uses an adaptive health check – not only the node itself but also consults its replicas – it can react really fast and promote the node in DC2.

Why is this problematic?

The problem occurs when

node01

resolves its temporary issue. A race condition could occur within ProxySQL that could mark it back as read-write. You can increase an …

MySQL 8.0 provides another way to handle JSON documents, actually in a "Not only SQL" (NoSQL) approach... In other words, if you need/want to manage JSON documents (collections) in a non-relational manner, with CRUD (acronym for Create/Read/Update/Delete) operations then you can use MySQL 8.0! Did you know that?

Introduction In this article, we are going to see how a relational database executes SQL statements and prepared statements. SQL statement lifecycle The main database modules responsible for processing a SQL statement are: the Parser, the Optimizer, the Executor. A SQL statement execution looks like in the following diagram. Parser The Parser checks the SQL statement and ensures its validity. The statements are verified both syntactically (the statement keywords must be properly spelled and following the SQL language guidelines) and semantically (the referenced tables and column do exist in the database). During... Read More

The post How does a relational database execute SQL statements and prepared statements appeared first on …

SQL Create Table Statement Example | Create Table in SQL Tutorial is today’s topic. A CREATE TABLE statement is used to create a new table in the database. SQL is the Standard Query Language for manipulating, storing and retrieving data in databases. SQL is used in MySQL, SQL Server, MS Access, Oracle, Sybase, Informix, Postgres, and other database systems. SQL stands for Structured Query Language. SQL lets you access and manipulates databases. RDBMS stands for Relational Database Management System. RDBMS is the basis for SQL, and for all modern database systems such as MS SQL Server, IBM DB2, Oracle, MySQL, and Microsoft Access.

SQL Create Table Statement Example

Working with SQL for data analysis and manipulation sometimes requires creating the new tables. Requirements like, Do you want to store the output of your SQL queries? Do you need to pull the new data sources (for example, csv files) into your data …

MariaDB Server 10.4 came with a whole lot of Security related changes. Some of them are merely optimizations (like MDEV-15649), some improve existing features to be more robust (MDEV-15473, MDEV-7598) or convenient (MDEV-12835, MDEV-16266). Some are MySQL compatibility features, requested by our users (MDEV-7597, MDEV-13095). But the first thing any MariaDB Server user, whether an […]

The post Authentication in MariaDB 10.4 — Understanding the Changes appeared first on MariaDB.org.

For some time, there have been several requests to the MySQL dev team to add dedicated support for an admin to connect to the MySQL server.  We received a contribution from Facebook, bug#90395 ,  to add this functionality, which we then paired with more requirements, implemented in WL#12138 and delivered in MySQL Server 8.0.14.…

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When your application get error "too many connections" underlying problem might be caused by multiple things. For a in-depth understanding of how MySQL handles connections read this blog.

In this blog we will investigate why and how to solve these problems when running MySQL installed on Debian/Ubuntu using systemd (default MySQL packages).

OS: Debian 9
MySQL Server version: 5.7.25 MySQL Community Server (GPL)
(will most likely be the same for MySQL 8.0 versions)

Goal is to have 10.000 working connections to MySQL!

The default value for max_connections is 151 connections so first step is to increase the max_connections variable to 10.000.
This is documented in the manuals here:
- https://dev.mysql.com/doc/refman/5.7/en/too-many-connections.html
- …

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Today is World Backup Day, so I thought I would use the opportunity to discuss some best practices and general considerations regarding backing up MySQL instances. While I focus on MySQL, several of these tips apply to backups in general.

Backup your data

Before heading into the gory details, let’s first take a look at the best practices at a high level:

• Make sure you can restore your backups:
  • Document and script the restore procedures. Do you know the steps required to restore a full backup – or a single table?
  • Keep copies of the backups off-site. Do you have a copy of your backup if the data center becomes unavailable for example due to a fire?
  • Validate your …

MySQL introduced Group Replication (GR) in version 5.7, and GR is part of the InnoDB Cluster high-availability solution. InnoDB Cluster consists of Group Replication, MySQL Shell and MySQL Router.

I am not going to explain InnoDB Cluster or Group Replication in this post. So, if you aren’t familiar with either one, I have some previous posts in which I have explained how to work with both. See:

MySQL 8.0 Group Replication – …

Why Choose MySQL Replication?

Some basics first about the replication technology. MySQL Replication is not complicated! It is easy to implement, monitor, and tune as there are various resources you can leverage - google being one. MySQL Replication does not contain a lot of configuration variables to tune. SQL_THREAD and IO_THREAD's logical errors aren't that hard to understand and fix. MySQL Replication is very popular nowadays and offers a simple way of implementing database High Availability. Powerful features such as GTID (Global Transaction Identifier) instead of the old-fashioned binary log position, or lossless Semi-Synchronous Replication make it more robust.

Related resources

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