You need to know where to find PostgreSQL logs. We usually suggest a few specific modifications to the postgresql.conf file for logging, including the following:
log_directory = 'pg_log' log_checkpoints = on
This means logs will be found within our PostgreSQL data directory, in a subdirectory named pg_log. Some distributions use /var/log/postgresql instead. Regardless, find where the logs are kept. To ensure access, examine these as the postgres user, who should either own the logs directly or have the necessary read access.
