alt Hacker NewsI am a DBA for Oracle databases, and XE can be used for free. It has the reference SQL/PSM implementation in PL/SQL. I know how to set up a physical standby, and otherwise I know how to run it.
That being said, Oracle Database SE2 is $17,500 per core pair on x86, and Enterprise is $47,500 per core pair. XE has hard limits on size and limits on active CPUs. XE also does not get patches; if there is a critical vulnerability, it might be years before an upgrade is released.
Nobody would deploy Oracle Database for new systems. You only use this for sunk costs.
Postgres itself has a manual that is 1,500 pages. There is a LOT to learn to run it well, comparable to Oracle.
For simple things, SQLite is fine. I use it as my secrecy manager.
Postgres requires a lot of reading to do the fancy things.
Postgres has a large manual not because it's overly complex to do simple things, but because it is one of the best documented and most well-written tools around, period. Every time I've had occasion to browse the manual in the last 20 years it's impressed me.