I guess that depends on what the log tables are used for.... Also in this case the logs are written to via a trigger.... I all within one transaction. So it may not matter.
We use UNLOGGED because the audit logs are not financial, and used only very rarely, and only for analysis of access and performance in a batch setting. Also certainly not via a trigger, as we don't want the logging bound to the transaction.
The idea here is to backup the rest of your DB to one backup regime and the log tables to another. We set it up so at the end of the day the current log table is backed up and loaded into an backup archive, then we vacuum freeze the log table.
Yeah, doing logging in-database for immediate performance while periodically copying or moving said data to external storage seems like the best option. Depends on the definition of an acceptable process and response time should the audit data be needed though.
