In this blog post, we’ll compare virtual columns in MySQL and MariaDB. Virtual columns are one of my top features in MySQL 5.7: they can store a value that is derived from one or several other fields in the same table in a new field. It’s a very good way to build a functional index. […]
Read More
Unlike MySQL 5.6, where parallel replication can only be used when replicas have several schemas, MySQL 5.7 replicas can read binlog group commit information coming from the master to replicate transactions in parallel even when a single schema is used. Now the question is: how many replication threads should you use? A simple benchmark Let’s […]
Read More
After we announced that Percona offers support for RocksDB, we saw many people looking for more details about this storage engine. Here is a quick list of some of the most frequent questions we get. Q: What is RocksDB? A: Quoting the homepage of the project: RocksDB is an embeddable persistent key-value store for fast storage. […]
Read More
I presented a talk at Percona Live Amsterdam a few weeks ago (simple recipes for your Galera cluster), and one of the topics was schema changes. I discussed the drawbacks and benefits of Total Order Isolation (TOI), Rolling Schema Upgrades (RSU) and pt-online-schema-change. One thing I forgot was online DDL from 5.6. Does it provide […]
Read MoreSeveral reports we’re published in the news about how easy it is to access data stored in some NoSQL systems, including MongoDB. This is not surprising because security was rather relaxed in earlier versions of MongoDB . This post lists some of the common vulnerabilities in MongoDB and Percona TokuMX. Network Security One key point […]
Read MorePercona Server 5.6.21+ and MySQL 5.7.8+ offer the super_read_only option that was first implemented in WebscaleSQL. Unlike read_only, this option prevents all users from running writes (even those with the SUPER privilege). Sure enough, this is a great feature, but what’s the relation with GTID? Read on! TL;DR Enabling super_read_only on all slaves when using […]
Read MoreI have heard this question quite often: “At busy times, our replicas start lagging quite frequently. We are using N schemas, so which performance boost could we expect from MySQL 5.6 parallel replication?” Here is a quick way to give you a rough estimate of the potential benefit. General idea In MySQL 5.6, parallelism is […]
Read MoreDuring the last couple of months I have been involved in an unusually high amount of performance audits for e-commerce applications running with Magento. And although the systems were quite different, they also had one thing in common: the MySQL query cache was very useful. That was counter-intuitive for me as I’ve always expected the […]
Read MoreI recently worked with a customer who had a weird issue: when their MySQL server was started (Percona Server 5.5), if they try to run service mysql start a second time, the init script was not able to detect that an instance was already running. As a result, it tried to start a second instance […]
Read MoreA question I often hear when customers want to set up a production PXC cluster is: “How many nodes should we use?” Three nodes is the most common deployment, but when are more nodes needed? They also ask: “Do we always need to use an even number of nodes?” This is what we’ll clarify in […]
Read More