PostgreSql Date Format

If you need change date format into postgres database, need execute next commands

SET DATESTYLE TO Postgres,US;
or
SET DATESTYLE TO iso,dmy --dd/mm/yyyy

this setting apply to current session; for permanent change modify postgresq.conf, section Locale and Formatting:

datestyle = 'iso, mdy'

Now you need reestart database

#service postgresql restart


Reload config settings without restarting database
If you are making modifications to the file postgresql.conf (or similar), and you want to new settings to take effect without needing to restart the entire database, there are two ways to accomplish this.

Option 1: From the command-line shell
#su - postgres
$/usr/bin/pg_ctl reload

Option 2: Using SQL

SELECT pg_reload_conf();

Using either option will not interrupt any active queries or connections to the database.

References:
[1] SET http://www.commandprompt.com/ppbook/r28464
[2] http://heatware.net/databases/postgresql-reload-config-without-restarting/