> The "relfilenode" attribute of the tuple contained the value
> "326210". I tried to find the file with that name in the
> database directory - it really was not there.
Did you look in lost+found?
> Thus, the backend crash has led not only to impossibility to
> complete my task, but also to loosing some data. The sequence
> was actually created in an already committed transaction, not
> in the one, that crashed.
How much time passed after sequence creation till crash?
Did you use -F (fsync = NO)?
Vadim