Hello everyone, in this little post we will review a new feature in MySQL 8.

What is “CHECK Constraint”?

This is a new feature to specify a condition to check the value before INSERT or UPDATE into a row. The constraint could return an error if the result of a search condition is FALSE for any row of the table (but not if the result is UNKNOWN or TRUE).

This feature starts working on MySQL 8.0.16, and in previous versions, we could create it, but it doesn’t work, meaning the syntax is supported but it is not working,

There are some rules to keep in mind…

– AUTO_INCREMENT columns are not permitted
– Refer to another column in another table is not permitted
– Stored functions and user-defined functions are not permitted (you can not call a function or any user-defined functions)
– Stored procedure and function parameters are not permitted (you cannot call …

Maybe one of the more “obscure” operations when dealing with replica lag, or, in general, when one needs to control writes to the database, is the Rate limit. It’s also lately one of the most popular conversations around the community.

But what is it? In plain words: holding up queries for a while, giving air to the replicas to breath and catch up. Something similar to the Galera’s Flow Control mechanism, although flow control, when it kicks in, stops all the writes while the nodes catch up. With a throttle no write is stopped, just delayed.

There are several ways to do this. A popular tool is Freno but this is also something that can be achieved with ProxySQL. Let’s see how.

Delay

ProxySQL has a variable called …

Watch the replay of this webinar about geo-distributed active/active MySQL replication for Financial Services SaaS Providers and on how to guarantee credit card transaction availability with geo-distributed Tungsten MySQL clusters.

Tags:  Webinar MySQL use case tungsten clustering mysql cluster bluefin MySQL Replication …

We look at some basics and follow up to present scenarios that require higher level intervention to ensure availability and to avoid split brains from taking place.

Read the full story

MySQL semi-sync is a plugin mechanism on top of asynchronous replication, that can offer better durability and even consistency (term defined later). It helps in high availability solutions, but can in itself reduce availability. We look at some basics and follow up to present scenarios that require higher level intervention to ensure availability and to avoid split brains from taking place. I recommend reading this semi-sync blog post by Jean-François Gagné (aka JFG), which illustrates the internals of the semi-sync implementation, and debunks some myths about semi-sync. We will overlap a bit with another recommended post by JFG, about high availability and recovery. Note: in this post we adopt the term “primary” over the term “master” in the context of MySQL replication. However, at this time there is no alternative to using the actual names of some configuration and status variables that use “master” terminology, and some duality is …

We look at some basics and follow up to present scenarios that require higher level intervention to ensure availability and to avoid split brains from taking place.

MySQL semi-sync is a plugin mechanism on top of asynchronous replication, that can offer better durability and even consistency (term defined later).

MySQL Database Service is now also available in India (Mumbai) and Canada (Toronto) Regions. These are additions to the Regions where the Service is already available: Brazil (Sao Paulo), Germany (Frankfurt), Japan (Tokyo), United Kingdom (London), United States East (Ashburn), and United States West (Phoenix).

If you want to test for free, go to oracle.com/cloud/free and get access to a wide range of Oracle Cloud services for 30 days, including MySQL Database Service in Ashburn, Frankfurt, London, Mumbai, Phoenix, Tokyo, and Toronto. Check the documentation for the quick steps to create your MySQL databases.

More Regions are coming soon. Stay tuned!

You are also welcome to register for the live MySQL Database Service webinar series: …

MySQL Database Service is now also available in India (Mumbai) and Canada (Toronto) Regions. These are additions to the Regions where the Service is already available: Brazil (Sao Paulo), Germany (Frankfurt), Japan (Tokyo), United Kingdom (London), United States East (Ashburn), and United States Wes...

In this post, we will discuss what to do when you add more memory to your instance. Adding memory to a server where MySQL is running is common practice when scaling resources.

First, Some Context

Scaling resources is just adding more resources to your environment, and this can be split in two main ways: vertical scaling and horizontal scaling.

Vertical scaling is increasing hardware capacity for a given instance, thus having a more powerful server, while horizontal scaling is adding more servers, a pretty standard approach for load balancing and sharding.

As traffic grows, working datasets are getting bigger, and thus we start to suffer because the data that doesn’t fit into memory has to be retrieved from disk. This is a costly operation, even with modern NVME drives, so at some point, we will need to deal with either of the scaling solutions we mentioned.

In this case, we will discuss adding more …