vacuum analyze crashes

Hi all,
i recently suscribed the bugs list and this is my first post to it. I
want to report a strange bug related to the 'vacuum analyze'
command.

Every time 'Vacuum analyze' find any table containing the value ''
(empty string) in the same column in two different rows it crashes
with the following error message:
pqReadData() -- backend closed the channel unexpectedly.
        This probably means the backend terminated abnormally
before or while processing the request.
We have lost the connection to the backend, so further processing
is impossible.  Terminating.


The following text reproduces the problem:

$ createdb test_db
$ psql test_db
Welcome to the POSTGRESQL interactive sql monitor:
  Please read the file COPYRIGHT for copyright terms of
POSTGRESQL

   type \? for help on slash commands
   type \q to quit
   type \g or terminate with semicolon to execute query
 You are currently connected to the database: test_db

test_db=> create table test (
test_db-> string1 varchar(10));
CREATE
test_db=> insert into test values ('test string');
INSERT 185001 1
test_db=> vacuum analyze;
VACUUM
test_db=> insert into test values ('');
INSERT 185003 1
test_db=> vacuum analyze;
VACUUM
test_db=> insert into test values ('');
INSERT 185005 1
test_db=> vacuum analyze;
pqReadData() -- backend closed the channel unexpectedly.
        This probably means the backend terminated abnormally
before or while processing the request.
We have lost the connection to the backend, so further processing
is impossible.  Terminating.


my conf:
postgres 6.4.2
linux 2.0.35 Intel
Pentium 233 192MB RAM


Antonio Garcia Mari
AT4.net Internet y Comunicación
http://www.at4.net/