Does UCS require PostgreSQL and what is it used for?
Question:
On a UCS 5.2 system, is PostgreSQL required? What purpose does it serve in UCS and is it used by default?
Answer:
Yes, PostgreSQL is required on UCS, even if no additional apps are installed. UCS uses PostgreSQL by default for its Package Tracking Database (PTDB).
The PTDB collects and stores the state and versions of packages installed across all systems in the UCS domain. This database ensures that package information can be centrally tracked and queried, which is important for consistency and domain-wide package management.
In addition to its role in the UCS base system, PostgreSQL is also used by several Univention App Center applications as their primary database backend. Examples include:
- Keycloak (depending on the version)
- Other third-party applications that require a relational database
How to check usage on your system:
- View installed applications:
univention-app info - Check the PostgreSQL service status:
systemctl status postgresql
Conclusion:
PostgreSQL is part of the UCS base system and is always required for the Package Tracking Database. Beyond that, its usage depends on which additional apps are installed on the system.
Further information:
Please refer to the UCS Developer Reference documentation:
UCS Developer Reference – PostgreSQL