Postgresql data archiving best practises

HI All

Me again ;-(

The second thing I need some info or assistance with is Data
archiving practises.

As per a previous post, our client have about 190 databases
which will be consolidated and some databases removed.

However one of our tasks is to do archiving of data.

As far as we have come so far they need to keep current year's
data + 5 years, and anything prior to this needs to be archived.

I do not have that much dba experience yet, and the rest of our
company focuses on Oracle.

The plan is to make proper full backups of the databases and
testing the backup restores before commencing.

Then we need to archive the data and test this afterwards.

However, we are concerned about the following:

- is there a way in postgresql to determine the table dependencies?
- In postgresql , how can we determine how old the data is (i.e.
what can be archived and what falls within the criteria)... the tables
mostly does not keep dates as part of the data itself so we need to
determine how to check this.

Once again all assistance is appreciated (from a learning postgresql dba)

Regards
Machiel