The latest from the MySQL community

Introduction In this article, we are going to see how we can limit the SQL query result set to the Top-N rows only. Limiting the SQL result set is very important when the underlying query could end up fetching a very large number of records, which can have a significant impact on application performance. Why limit the number of rows of a SQL query? Fetching more data than necessary is the number one cause of data access performance issues. When a given business use case is developed, the amount of data available... Read More

The post How to limit the SQL query result set to Top-N rows only appeared first on Vlad Mihalcea.

ProxySQL 2.0.5, released by ProxySQL, is now available for download in the Percona Repository along with Percona’s proxysql-admin tool.

ProxySQL is a high-performance proxy, currently for MySQL and database servers in the MySQL ecosystem (like Percona Server for MySQL and MariaDB). It acts as an intermediary for client requests seeking resources from the database. René Cannaò created ProxySQL for DBAs as a means of solving complex replication topology issues.

This release includes ProxySQL 2.0.5 which fixes many bugs and introduces a number of features …

In reply to Jame.

I’m glad the post helped you to get the problem fixed!
And I hope you enjoyed the breakfast 😀

LikeLike

An impressive share! I’ve just forwarded this onto a co-worker who had been doing a little research on this.
And he in fact ordered me breakfast due to the fact that I discovered it for him…

lol. So allow me to reword this…. Thanks for the meal!!
But yeah, thanx for spending some time to discuss
this topic here on your internet site.

LikeLiked by 1 person

To set correct system variable values is the essential step to get the correct server behavior against the workload.  

In MySQL we have many System variables that can be changed at runtime, most of them can be set at session or at global scope. 

To change the value of a system variable at global level in the past user need to have SUPER privileges. Once the system variable value is modified as global, the server will change his behavior for the session, and obviously as global scope. For instance, one of the most commonly adjusted variables is probably max_connections. If you have max_connection=100 in your my.cnf or as default value, and during the day as DBA you notice that the number of them is not enough, it is easy just to add new connections on the fly, the command:

SET GLOBAL MAX_CONNECTIONS=500;

Will do the work. But here is the issue. We had changed a GLOBAL value, that apply to the whole …

To set correct system variable values is the essential step to get the correct server behavior against the workload.  

In MySQL we have many System variables that can be changed at runtime, most of them can be set at session or at global scope. 

To change the value of a system variable at global level in the past user need to have SUPER privileges. Once the system variable value is modified as global, the server will change his behavior for the session, and obviously as global scope. For instance, one of the most commonly adjusted variables is probably max_connections. If you have max_connection=100 in your my.cnf or as default value, and during the day as DBA you notice that the number of them is not enough, it is easy just to add new connections on the fly, the command:

SET GLOBAL MAX_CONNECTIONS=500;

Will do the work. But here is the issue. We had changed a GLOBAL value, that apply to the whole …

MySQL Memory Calculator

Check out the “MySQL Memory Calculator” added to my blog page, which will be helpful to calculate MySQL memory usage during tuning of MySQL memory parameters. https://www.abhinavbit.com/p/mysql-memory-calculator.html

Photo by Kelly Sikkema on  …

Through Amazon Web Services (AWS), you can create virtual servers (i.e., instances). You can install database and Galera software on them. In this article, we’ll create three nodes, the minimum recommended for a healthy cluster, and configure them to use Galera Cluster.

Incidentally, there is a more detailed version of this article in the Tutorial section of our Library.

Assumptions & Preparation

We’re assuming you have an AWS account and know the basics of the EC2 (Elastic Compute Cloud) platform.

To access the nodes, you’ll need an encryption key. Create a new one specifically for Galera, using a tool such as ssh-keygen. Add that key to AWS, under Key Pairs.

Creating AWS Instances

To …

Overview The Skinny

Part of the power of Tungsten Clustering for MySQL / MariaDB is its intelligent MySQL Proxy, known as the Tungsten Connector. The Tungsten Connector has built-in read-write splitting capabilities, and it is also possible to configure different algorithms which select the appropriate slave (i.e. Round-Robin or Lowest-Latency).

The Question Recently, a customer asked us:

How do we best share the load between read-only slaves? Currently, there appears to be an imbalance, with most of the read-only queries reaching just one slave. What may we do to improve this situation?

This customer noticed that a couple of long …