Using Epoch to save timestamps in 4 bytes?

[Francisco Reyes <lists@xxxxxxxxxxxxxxxx>]

While looking at a database I inheritted I noticed the database has tables 
with integers used to store epoch.

I noticed that timestamp is 8 bytes and was wondering how come timestamp is 
8 bytes and not 4. Is it to be able to support precission beyond a second?

I am looking at tens of millions of rows, which is why my predecessor may 
have used integer to store epoch to save space.