Alain Picard <Alain.Picard@memetrics.com> writes:
> Behold!
> select * from test_table
> where data !='bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb'
> and
> data != 'aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa';
> -> returns:
> id | data
> --------+------------------------------------------------------------------
> 253084 | bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbâbbbbbbbbbbbbbbbbbbbbbbb
> 55068 | áaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
> (2 rows)
I would say that you have either faulty RAM or a faulty disk drive.
Given the apparent dependence on running more than one backend at a
time, faulty RAM is perhaps more likely (the bad chip could be in
RAM locations that don't get used unless lots of processes are running).
The apparent single-bit nature of the fault also points to a bad RAM
location; disks tend to drop multiple words or whole sectors, not
single bits. But dropped bits during I/O transfers shouldn't be ruled
out completely.
Have you run any hardware diagnostics lately?
regards, tom lane
