Search Results for: update set case when

Free MySQL QA & Bash/Linux Training Series

Welcome to the MySQL QA Training Series! If you have not read our introductory blog post on pquery yet, I’d recommend reading that one first to get a bit of background. The community is enthuastic about pquery, and today I am happy to announce a full training series on pquery and more. Whether you are […]

Advanced JSON for MySQL

What is JSON JSON is an text based, human readable format for transmitting data between systems, for serializing objects and for storing document store data for documents that have different attributes/schema for each document. Popular document store databases use JSON (and the related BSON) for storing and transmitting data. Problems with JSON in MySQL It […]

5 free handy tools for monitoring and managing MySQL replication

MySQL Replication is very simple to set up. In this post I’ll discuss its importance and five handy tools for monitoring and managing MySQL replication. What is MySQL Replication? It’s the process of copying the (real-time events) data from one master instance to another slave instance and maintaining the redundant consistent data in a different […]

Improving Percona XtraDB Cluster SST startup with Google Compute Engine snapshots

As the need for information grows so does the size of data we need to keep in our databases. SST is unavoidable for spinning up new nodes in a PXC cluster and when datasets reach the “terra-byte” range this becomes ever more cumbersome requiring many hours for a new node to synchronize. More often that not, […]

Using MySQL Event Scheduler and how to prevent contention

MySQL introduced the Event Scheduler in version 5.1.6. The Event Scheduler is a MySQL-level “cron job”, which will run events inside MySQL. Up until now, this was not a very popular feature, however, it has gotten more popular since the adoption of Amazon RDS – as well as similar MySQL database as a service offerings […]

Looking deeper into InnoDB’s problem with many row versions

A few days ago I wrote about MySQL performance implications of InnoDB isolation modes and I touched briefly upon the bizarre performance regression I found with InnoDB handling a large amount of versions for a single row. Today I wanted to look a bit deeper into the problem, which I also filed as a bug. First […]

MySQL performance implications of InnoDB isolation modes

Over the past few months I’ve written a couple of posts about dangerous debt of InnoDB Transactional History and about the fact MVCC can be the cause of severe MySQL performance issues. In this post I will cover a related topic – InnoDB Transaction Isolation Modes, their relationship with MVCC (multi-version concurrency control) and how […]

Using YUM to install specific MySQL/Percona Server versions

Sometimes it is desired to use particular software versions in production, and not necessary the latest ones. There may be several reasons for that, where I think the most common is when a new version should spend some time in testing or a staging environment before getting to production. In theory each new version is […]

The MySQL Query Cache: How it works, plus workload impacts (good and bad)

Query caching is one of the prominent features in MySQL and a vital part of query optimization. It is important to know how it works as it has the potential to cause significant performance improvements – or a slowdown – of your workload. The MySQL query cache is a global one shared among the sessions. It caches […]

How small changes impact complex systems – MySQL example

If you’ve been studying complex systems you know what minor changes might cause consequences of much greater proportions, sometimes causing some effects that are not easily explained at first. I recently ran across a great illustration of such behavior while doing MySQL benchmarks which I thought would be interesting to share. I’m using a very […]