Having trouble with backups (was: Re: Crash Recovery)

Speaking about daily backups...  We are running into some serious
trouble with our backup policy.

First (and less important), the size of our backups is increasing
a lot;  yet information is not changing, only being added;  so, the
obvious question:  is there a way to make incremental backup?

And the second (and intriguing) problem:  whenever I run pg_dump,
my system *freezes* until pg_dump finishes.  When I say "system",
I mean the software that is running and sending data to the PG
database.  It just freezes, users are unable to connect during
several minutes, and the ones already connected think the server
died, so they end up disconnecting after one or two minutes
seeing that the server does not respond.

Is this normal?  Is there any way to avoid it?  (I guess if I
have a solution to the first problem -- i.e., doing incremental
backups -- then that would solve this one, since it would only
"freeze" the system for a few seconds, which wouldn't be that
bad...)

Thanks for any comments!

Carlos
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