Re: Postgres 7.2.2 Segment Error

"Christopher Kings-Lynne" <chriskl@familyhealth.com.au> writes:
> I just saw this in my logs:
> 2002-09-18 12:13:10 ERROR:  cannot open segment 1 of relation users_sessions
> (target block 1342198864): No such file or directory

> This query caused it:

> DELETE FROM users_sessions WHERE changed < ('now'::timestamp - '1440
> minutes'::interval)  AND name = 'fhnid';

What does EXPLAIN show as the plan for that query?  I'm guessing an
indexscan, and that the error was caused by reading a broken item
pointer from the index.  (1342198864 = hex 50005450, which sure looks
like the upper 5 shouldn't be there ... how big is the table, anyway?)

> However, I cannot repeat the error now.  Is this a bug in postgres
> somewhere.

If the broken item pointer were indeed in the index, I'd expect it to be
100% repeatable.  I'm wondering about flaky memory or some such.  Have
you run any hardware diagnostics?
        regards, tom lane