The MacFlow example postgresql section contains inconsistent logfile locations.

the instructions suggest createing a logs folder but later suggests:

Start the Postgres server
<YourServerName>:pgsql postgres$ /usr/local/pgsql/bin/pg_ctl -D /usr/local/pgsql/data -l
 /usr/local/pgsql/data/postgres.log start

A few lines down the instructions revert to:

Stop the server

<YourServerName>:pgsql postgres$ /usr/local/pgsql/bin/pg_ctl -D /usr/local/pgsql/data -l
   /usr/local/pgsql/logs/logfile stop

and to start it again:

<YourServerName>:pgsql postgres$ /usr/local/pgsql/bin/pg_ctl -D /usr/local/pgsql/data -l
 /usr/local/pgsql/data/logs/logfile start