(Rob Gravelle) A cross tabulation query, or cross tab/crosstab for short, is used to display the result of an aggregation on two or more fields. The trick to this type of query is the transformation of rows of data to columns.

(Dave Stokes) MySQL has had a JSON data type since version 5.7 was released way back in ’15. But did you know you could produce JSON output from non-JSON columns? It is very simple and saves a lot of time over trying to format it in your application.

(Valerie Parham-Thompson) I’ve done dutiful DBA work in the past to identify and remove what are commonly called duplicate indexes. That is, those indexes that look like (a) and (a,b).

(Art van Scheppingen) Having too large a (write) workload on a master is dangerous. If the master collapses and a failover happens to one of its slave nodes, the slave node could collapse under the write pressure as well. To mitigate this problem you can shard horizontally across more nodes.

(Preetam Jinka) We’ve been having a problem with MySQL replication at VividCortex. Replicas periodically tend to fall behind and we couldn’t really figure out how to speed things up. It wasn’t about resources. The replicas have plenty of CPU and I/O available. We’re also using multithreaded replicat

(Daniel Guzmán Burgos) This post discusses enabling and disabling jemalloc on Percona Server for MySQL.

(Frederic Descamps) Today’s blog post is related again to MySQL Group Replication.

(Dimitri Vanoverbeke) This blog provides a query language type overview.

(Krzysztof Ksiazek) In the previous blog post, we discussed how gh-ost works internally and how it compares to Percona’s pt-online-schema-change. Today we’d like to focus on operations – how can we test a schema change with gh-ost to verify it can be executed without any issues? And how do we go ahe

(Jaime Sicam) In a previous article, Ovais demonstrated how a DDL can render a table blocked from new queries. In another article, Valerii introduced performance_schema.metadata_locks, which is available in MySQL 5.7 and exposes metadata lock detail