BUG #5736: 9.0.1 segmentation fault (sig11) during long-lived update

The following bug has been logged online:

Bug reference:      5736
Logged by:          Henry
Email address:      henka@cityweb.co.za
PostgreSQL version: 9.0.1
Operating system:   Linux
Description:        9.0.1 segmentation fault (sig11) during long-lived
update
Details:

Hi,

I'm using PostgreSQL 9.0.1 on centos 5.4.

I'm running the following update (which takes a few days to run before I get
the error - twice now):

update tab1 set col1 = hashtext(col0) where col1 isnull;

I'm running this update as part of an exercise to purge duplicates, before
creating a UNIQUE index.

Error from PG:

server process (PID 19328) was terminated by signal 11: Segmentation fault
terminating any other active server processes
...

Before I run this again, what's the best way to proceed to get a core dump
so I can run a gdb backtrace to provide more info?  Simply 'ulimit -c
5242880' as user postgres and restart PG?

Thanks