This is only a short introduction to PostgreSQL. This section should not replace the reading of the PostgreSQL Administration Guide but after the lecture of this section you should be able to setup OpenCA very easily with a real datbase and not only with DBM files. This is important because PostgreSQL has transaction support which is essential for serious database applications.
If we talk about real world databases then it is a good idea to mention pgadmin III. The old versions pgadmin I and II only support windows. The third version supports Unix too. So there is now a GUI like for MySQL available which can be used to manage the database. There are people who think that GUIs are not necessary but they enhance the management of several things a lot because not everybody has the time and skill to optimize it's PostgreSQL database perfectly.
Another note about security, please never trust database security mechanisms fully. Use at every time a small IP-firewall in front of your database server. The default installation of OpenCA is a datbase server on localhost. If you want to install a database server on a different machines than the OpenCA components then always install these servers at minimum in a DMZ. Databases like PostgreSQL has today it's own strong security mechanisms but they have from time to time some big bugs. OS-based IP-filters like ipf or netfilter are usually more robust.
large object are included
create the database newly on recovery
export all data as insert commands to support on the fly database mogration
columnname based inserts to support rearrangement of column ordering
DBM file are much easier to handle than real SQL databases. If you want to use these database then you must only ensure that the directory which should contain the database files is fully writeable, readable and accessible by the webserver user. This will be handled by OpenCA's installation routine automatically. Sometimes in the past the users choose the wrong webserver user. The result is a message in the logs that the function configError doesn't exist. This happens because the OpenCA script cannot load the library files. The new versions of OpenCA (0.9.1.4+) display correct errormessages in this case. Extra actions by the installing administrator are not necessary.
Please never forget that DBM files don't support transactions. If you implement a real world PKI then it is strongly recommend to use SQL databases to have a consistent state of the PKI even in the case of a system crash. DBM has also problems with multi user access for example on web servers with high loads.