Any way to figure out why a session stopped?

Greetings-

I was running a large job, started on Wednesday evening. The job, which
used a perl script and DBI to do some manipulation and pattern extraction
from full-text documents in a PostgreSQL database (version 7.1.3, running
on debian linux), stopped about 1/3 of the way through its task.

Unfortunately, I don't still have the window open from which I ran the
script. Is there any way to figure out why it stopped, and thereby fix the
problem? There's nothing very illuminating in /var/log/postgres.log, and
from psql I can insert rows into all the tables, so I don't think it was
an issue of the tables growing too big.  However, they are very big, so if
that rings any bells let me know:

auth=# select count(*) from patterns;
  count
---------
 2720343
(1 row)

auth=# select count(*) from pattern_occurrences;
  count
---------
 3176859
(1 row)


There is, though, plenty of disk space for them to play with:

aperrin@hm269-26876:~$ df /var/lib/postgres/data
Filesystem           1k-blocks      Used Available Use% Mounted on
/dev/hda3              9614148   3675684   5450088  41% /


----------------------------------------------------------------------
Andrew J Perrin - andrew_perrin@unc.edu - http://www.unc.edu/~aperrin
 Assistant Professor of Sociology, U of North Carolina, Chapel Hill
      269 Hamilton Hall, CB#3210, Chapel Hill, NC 27599-3210 USA