Restoring database disk space requirements???

Hi!

I seem to be having a problem. I have a database that is around 10 GB
in size. I have it running on a 40 Gb disk. I tried to dump and
restore two of the tables, around 4 GB in size. All went find, the
file approximately 5 GB in size was created. No problem. I wanted to
import the data into another database.

However, when I try to import the database, the disk fills up with
about 20 GB of files in the pg_xlog directory, and the postmaster
crashes out. The only way to get anything to run then is to kill those
files, after which postgres refuses to start. the only way to get it
to work again is to delte the files in /var/lib/pgsql/data and re-run
initdb.

Unfortunately, when I try to restore the backed up data, the same
thing happens.

Can somebody please explain to me why is it that 20 Gb of disk space
is required to restore 5 GB of data? I am guessing that WAL is
creating those files, but with the 64 file limit in the config file,
and each file being 16 MB, that should only ever be up to 1 GB - NOT
20 GB!

What is going on? I have had this same problem with v7.0, and now with
v7.1. Is there an obscure section in the docs that I have missed?

Cheers.

Gordan