A sold out, two-day event with over 30 sessions on various aspects of MySQL is a tough thing to organize and accomplish. But the MySQL pre-FOSDEM Days was an amazing success. If you missed this event then you really missed two full days of presentations by MySQL engineers and subject matter experts from the MySQL Community. 


It all started on Thursday January 30th with Geir Hoydalsvik talking about Simplifying MySQL which not a simple talk.  Big efforts are being made to clean up and modernize the MySQL Server Core code.  Work is being undertaken to change to a Volcano Model for extended flexibility. 

This was followed by Kenny Gryp showing how the new InnoDB Replica Set. Previously it was easier to setup InnoDB Cluster Replication than simple …

i was working on some example code for using check constraints and was fairly happy with my first bit of of code.

CREATE TABLE c1 (x INT 
                   CONSTRAINT x_gt_0 CHECK (x > 0)
);

it worked well and did what I wanted which was to reject data where the value for x was not one or greater. MySQL has allowed you to have constraint checks for many years but they only came to life in 8.0.16.  Before that version the checks were simply ignored.

So I was writing some more demo code and smacked into what I thought was an odd error.

CREATE TABLE c2 (x INT 
                   CONSTRAINT x_gt_0 CHECK (x > 0), 
                   CONSTRAINT …

Codership is pleased to announce a new Generally Available (GA) release of Galera Cluster for MySQL 5.6 and 5.7, consisting of MySQL-wsrep 5.6.47 (release notes, download) and MySQL-wsrep 5.7.29 (release notes, download) with a new Galera Replication library 3.29 (release notes, download), implementing wsrep API version 25. This …

This is the tutorial and serves as a sample ONLY.  Every environment can be different.  It is a test trial for the Upgrade MySQL InnoDB Cluster with version 5.7.25 to MySQL 8.0.19 where the MySQL InnoDB Cluster Metadata has changed from V1 to V2 in 8.0.19.
1.      Assuming the following SETUP            i.              MySQL Server 5.7.25           ii.              MySQL Shell : 8.0.15         iii.              MySQL Router : 8.0.15 2.      3 nodes are running on the same machine for this tutorial            …

Monitoring is a must in all environments, and databases aren’t the exception. Once you have your database infrastructure up-and-running, you’ll need to keep tabs on what’s happening. Monitoring is a must if you want to be sure everything is going fine but also if you make necessary adjustments while your system grows and evolves. That will enable you to identify trends, plan for upgrades or improvements, or react adequately to any problems or errors that may arise with new versions, different purposes, and so on.

For each database technology, there are different things to monitor. Some of these are specific to the database engine, vendor, or even the particular version that you’re using. Database clusters heavily depend on the underlying infrastructure, so network and operating stats are interesting to see by the database administrators too. 

When running multiple database systems, the monitoring of these systems can …

MySQL 8.0.19 introduces Binlogless replicas with commit ordering which means you can deploy asynchronous replicas without binary logs enabled, and commit transactions in the same order they are replicated in. Yes, you can disable binlog (skip-log-bin) and the logging of changes done by the applier (log-slave-updates=FALSE) while at the same preserve commit order (slave-preserve-commit-order=TRUE).…

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As hinted at earlier this month, we’re happy to announce our latest on-demand webinar:
“An Introduction to Database Proxies (for MySQL)”

In this webinar, Gilles Rayrat, our VP of Engineering and database proxies guru, shares some of his knowledge on the world of database proxies, how they work, why they’re important and what to use them for.

Starting with a simple database connectivity scenario, Gilles builds up the content by discussing clustered databases and what happens in the case of a failure through to explaining the important role database proxies play; including a more in-depth look into some advanced database connectivity setups and proxies functionalities.
…

Introduction In this article, we are going to see how the SQL EXISTS operator works and when you should use it. Although the EXISTS operator has been available since SQL:86, the very first edition of the SQL Standard, I found that there are still many application developers who don’t realize how powerful SQL subquery expressions really are when it comes to filtering a given table based on a condition evaluated on a different table. Database table model Let’s assume we have the following two tables in our database, that form a one-to-many... Read More

The post SQL EXISTS and NOT EXISTS appeared first on Vlad Mihalcea.

Introduction to InnoDB Cluster

If you have not heard about MySQL InnoDB Cluster MySQL, InnoDB Cluster is a built-in high-availability solution for MySQL. The key benefit over old high-availability solutions is that InnoDB Cluster is built into MySQL and supported on all platforms where MySQL is supported.

The key components of MySQL InnoDB Cluster:
- MySQL Group Replication
- MySQL Shell
- MySQL Router

MySQL Group Replication is a plugin that makes sure that; data is distributed to all nodes, conflicts are handled and also recovery if needed.
MySQL Shell makes is easy to configure and administer your InnoDB Cluster.
MySQL Router is the last part of InnoDB cluster, it's a lightweight middleware that provides transparent routing between the application and back-end MySQL Servers part of group replication.

If you want to get started …

In one of our previous blogs we explained how Clone Plugin, one of new features that showed in MySQL 8.0.17, can be used to rebuild a replication slave. Currently the go-to tool for that, as well as for backups, is Xtrabackup. We thought it is interesting to compare how those tools work and behave.

Comparing Performance

The first thing we decided to test is how both perform when it comes to storing the copy of the data locally. We used AWS and m5d.metal instance with two NVMe SSD and we ran the clone to local copy:

mysql> CLONE LOCAL DATA DIRECTORY='/mnt/clone/';

Query OK, 0 rows affected (2 min 39.77 sec)

Then we tested Xtrabackup and made the local copy:

rm -rf …