Some believe the most important part of SQL is the ability to query data. Queries typically retrieve data by joining many tables together into useful result sets. This tutorial takes the position that visibility into the data helps those new to SQL understand how joins work. To that end, the queries use Common Tabular Expressions (CTEs) instead of tables.

Default behavior of a JOIN without a qualifying descriptor is not simple because it may return:

• A CROSS JOIN (or Cartesian Product) when there is no ON or USING subclause, or
• An INNER JOIN when you use an ON or USING subclause.

The following query uses JOIN without a qualifier or an ON or USING subclause. It also uses two copies of the single CTE, which is more or less a derived table and the result of a subquery held in memory. This demonstrates the key …

ProxySQL is proud to announce the latest release of ProxySQL version 2.0.16 on the 26th of January 2021

ProxySQL is a high performance, high availability, protocol aware proxy for MySQL, with a GPL license! It can be downloaded here or alternatively from the ProxySQL Repository, or the Docker image available on our Official ProxySQL Docker Repository.  ProxySQL is freely usable and accessible according to the GNU GPL v3.0 license.

Release Overview Highlights

ProxySQL v2.0.16 is a patch release comprising of minor backward compatible changes and bug fixes. This release brings several fixes to ProxySQL’s Native Galera monitor, AWS Aurora and connection handling.

…

MySQL Replication is a very common topology, widely used in various architecture.
People use it, among others, for High Availability, Read Scalability or Geographic Redundancy.

Another use case is to use MySQL Replication to seamlessly integrate a newer version of the server in your architecture.
Let’s say you are running MySQL 5.7 then you can easily setup a 8.0 instance as a replica of your 5.7.

Extending this idea it is also possible to replicate your MySQL 5.7 (or 8.0 obviously) to a MySQL Database Service instance, the true MySQL PaaS on Oracle Cloud Infrastructure.

The post Replicate from MySQL 5.7 to MySQL Database Service first appeared on dasini.net - Diary of a MySQL experts.

In MySQL Server 8.0.23 an improvement was made to InnoDB that allows truncation and deletion of all tablespaces to be faster. In fact, making it almost instantaneous as long as AHI is disabled. This is done by allowing pages in the buffer pool to be freed lazily instead of immediately when a tablespace is deleted.…

Facebook Twitter LinkedIn

On behalf of the Vitess maintainers team, I am pleased to announce the general availability of Vitess 9. Major Themes # In this release, we have focused on making Vitess more stable after the successful release of Version 8. There have been no major issues reported. So there were no patches released for Version 8. This has allowed us to push further on compatibility and adoption of common frameworks as priorities.

We recently saw how the new Invisible Column feature works in MySQL since 8.0.23 and how we can use it as a Primary Key for InnoDB tables when no Primary Key was defined.

As I wrote earlier, a good Primary Key is important for InnoDB (storage, IOPS, secondary indexes, memory…) but there is another important domain where a Primary Key is important in MySQL: replication !

Asynchronous Replication

When using “traditional” replication, if you modify a record (UPDATE and DELETE), the record(s) to modify on the replica are identified using indexes, and of course the Primary Key if any. The hidden global 6-bytes auto generated by InnoDB primary key is never used as never exposed and as it’s global, …

Although how range_optimizer_max_mem_size operates is explained in the official doc, it’s not a well-known variable and surely not a variable you need to modify under most circumstances. But from time to time we get some performance tickets related to this.

What problem does this variable cause if it is not properly sized? Let’s find out with an example!

Given the following table definition:

CREATE TABLE `joinit` (
  `i` int(11) NOT NULL AUTO_INCREMENT,
  `s` varchar(64) DEFAULT NULL,
  `t` time NOT NULL,
  `g` int(11) NOT NULL,
  PRIMARY KEY (`i`)
) ENGINE=InnoDB AUTO_INCREMENT=2490316 DEFAULT CHARSET=latin1

With ~2M rows

select count(*) from joinit ;
+----------+
| count(*) |
+----------+
|  2097152 |
+----------+

With the default value of  range_optimizer_max_mem_size = 8388608, the following …

… an expedition to uncover (and fix) database performance issues!

© 2021 Tiago L. Alves. All rights reserved.

One of the worse things that can happen when upgrading to a newer database version is discovering that the performance is not as good as before. Despite the effort put into gate-keeping MySQL NDB Cluster’s strict performance requirements, one of our customers found a performance regression when upgrading from our 7.4 version to our 7.6 version. How did that happen when our automated performance test suite failed to show it? To answer that, and fix the issue we enrolled on a database performance archaeology expedition…

When your performance is not good enough

MySQL NDB Cluster is an open-source in-memory distributed database developed for high-availability (99.999% or more) and predictable query times. It can be found at the core of gaming, banking, telecommunication, and online services. …

This article is the second part of the series related to MySQL Invisible Column started here.

This post covers why Invisible Column is important for InnoDB Storage Engine.

To start, let me explain briefly how InnoDB deals with Primary Key and why an good primary key is important. And finally, why having a Primary Key is also important.

How does InnoDB Stores Data?

InnoDB stores data in table spaces. The records are stored and sorted using the clustered index (the primary key): they are called index-organized tables.

All secondary indexes also contain the primary key as the right-most column in the index (even if this is not exposed). That means when a secondary …

The MySQL Development Team is happy to announce a new 8.0 Maintenance Release of MySQL Shell AdminAPI – 8.0.23!

In addition to several bug fixes and minor changes, some significant enhancements regarding monitoring/troubleshooting and performance were included.

MySQL Shell AdminAPI Cluster diagnostics

Checking how a Cluster is running and, whenever the cluster is not 100% healthy, perform troubleshooting tasks is certainly one of the main tasks of a DBA.…

Facebook Twitter LinkedIn