Relational Databases
Still the default, and still the right default. The relational model buys transactions, constraints the database enforces on every writer, and a query planner that reorganises work you did not have to think about. Most arguments for leaving it turn out to be arguments about one query.
PostgreSQL
The one to reach for. Extensible enough that several other families on this page are reachable from it without running a second server: Geographic Information Systems through PostGIS, Time Series Databases through TimescaleDB, JSON documents natively.
The deep dive is on PostgreSQL.
MySQL
Still enormously deployed. Sun bought MySQL AB in February 2008; Oracle announced its acquisition of Sun on 20 April 2009 and closed it on 27 January 2010. MariaDB was forked in between, by original author Michael Widenius, in anticipation rather than reaction - its first release, 5.1.38, shipped on 29 October 2009, three months before Oracle actually owned the code.
Note the version numbers if you are pinning: the newest tag in the
repository is mysql-26.7.0 (2026-07-28), straight after
mysql-9.7.2.
Query engines over other people’s data
Distributed SQL over object storage and existing databases, rather than a store of its own: Presto and Trino.
Reference
- How f*cked is my database - a decision tree, and funnier than it has any right to be.