database/table snapshot

Hey folks,

I wonder, how would you guys approach table snapshots.
So the thing is, I have table X (I have few more tables, but lets
simplify that). That table is being replicated to X' on other server.
Now I need an ability to see changes, say every interval T. So, the
simplest solution would be to insert all that data to table Xs, with
additional time column,
but that obviously will take vast amounts of space. Is there any
existing algorithm for doing that, or perhaps there's something in
postgres that would allow me to do it - but I don't know about ?
thx.


--
GJ