question about large databases

Hi, List!

Some times ago in this list was discussed next question: Which databases are small and which are large?

The answer was:
1-2 GB - small
50 and around - large

As I think, hundreds of GB and more - very large (VLDB).

How Postgres works with VLDB? And what about speed? Can I expect that postgres works with VLDB not worse that commertial DBMS (DB2, Oracle, Informix). Maybe someone have a comparision results of Postgres, DB2, Oracle and Informix (or postgres and any of commertial DBMS) when this DBMS manage with VLDB? I will VERY, VERY respect to that man for the information...

My organisation plans to use GIS based on PostGIS/Postgres. As we think, size of our database can be 50, 100 and more Gb.

Thanks in advance!

Sergey Karin