Under SELinux, network connection for HTTP server needs to be enabled

At http://drupal.org/documentation/install/create-database there should be paragraph about SELinux.
In current configuration through web, there is no possibility to use unix domain socket connection. Only "localhost" which means only TCP connection to PostgreSQL server is available. But with SELinux, this is impossible without permitting HTTP server do make network connection. So this command should be issued as root after database is created:

setsebool -P httpd_can_network_connect 1

There should be possibility to use unix domain socket, as PHP can do this (by not specify hostname and "localhost" when creating connection to the SQL server for both PosgreSQL and MySQL). And unix domain socket does not eats network overhead for talking to SQL server.