Thread: syncronization

hi;
i am trying to make a utility that is worked as database
synchronization.

there are 5 offices in  different states and all they use same database
means (same structure table).
there is a head office where is central server that is maintained all
offices databases seprately.

now i think following options for that utility :-

1)    at the end of the each day all the offices are sent the     backup
through pg_dump to the head office and update the central     server. (is
it worked on Wide Area Network efficiently)

2)    is there any command in postgresql that display all the queries     on a
particular day.


or any other option/suggestion that i should follow to make this utility

please help me.
thank you