PuppetDB logging is managed by the config file located at /etc/puppetlabs/puppetdb/logback.xml on the PuppetDB server. This logback file contains entries for the following logs, which are in /var/log/puppetlabs/puppetdb/, by default:
- puppetdb.log: Information on the PuppetDB application
- puppetdb-access.log: Information on user and machine access to PuppetDB
- puppetdb-status.log: Current status of PuppetDB
If you're looking for postgresql logs, they're contained in /var/log/puppetlabs/postgresql. This is standard postgresql logging.