etc/postgresql/9.1/main/pg_ident.conf

   1 # MAPNAME  SYSTEM-USERNAME  PG-USERNAME
   2 admin      postgres         postgres
   3 admin      root             postgres
   4 role       postgres         davical_dba
   5 role       php5_davical     davical_app
   6 user       postgres         agendav
   7 user       root             roundcube
   8 user       /^php5_(.*)$     \1
   9 user       /^(.*)$          \1