So there was a postgresql update where the data format was incompatible. That happens regularily and is ... acceptable, I guess (even more acceptable in guix because I can easily switch back to the old release).
However, in order to find that out, I had to: $ psql ... something about a socket not being reachable $ sudo herd status postgres Status of postgres: It is started. Running value is 18438. It is enabled. Provides (postgres). Requires (user-processes loopback). Conflicts with (). Will be respawned. So it claimed that everything was just peachy. $ sudo herd stop postgres $ sudo herd start postgres ... which reported nothing out of the ordinary either. $ ps -ef |grep postgres [xxxx] <defunct> Aha! finally an indication that something is amiss. So I tried to find the log entries, to no avail so far. (I found: /gnu/store/b073csgl56g2wnq7azj4wrswb6azsvc0-postgresql-9.5.1/bin/pg_ctl -D /var/lib/postgresql/data -l logfile start, not sure how that helps) $ man pg_ctl No manual entry for pg_ctl In the mean time, I decided I can just start up the postgres server process manually and it will tell me. $ postgres --config-file=/etc/postgresql.conf -D /var/lib/postgresql/data FATAL: data directory "/var/lib/postgresql/data" has wrong ownership HINT: The server must be started by the user that owns the data directory. $ sudo -i # su - postgres Password: errr... what password? # passwd postgres ... # su - postgres Password: su: Authentication failure # passwd -u postgres # su - postgres Password: This account is currently not available. Hmmm... $ sudo -u postgres postgres --config-file=/etc/postgresql.conf -D /var/lib/postgresql/data FATAL: database files are incompatible with server DETAIL: The data directory was initialized by PostgreSQL version 9.3, which is not compatible with this version 9.5.1. $ Aha! It says so right there in the standard output (or error?). Where did that message go in the shepherd case? $ cd /var/log $ grep -r incompatible . $ ??? Anyway, it works again now but we shouldn't have to do this kind of digging.
