"Guillaume MARTIN" <guillaume@eurovox.fr> writes:
> Today, I made a vacuum but the following error occured :
> FATAL 2: open of /var/pgsql/data/pg_clog/0022 failed: No such file or dire=
> ctory
Hm, what PG version is this exactly? 7.2 or 7.2.1?
> In the pg_clog directory, i've got 6 files :
> 0025
> 0026
> 0027
> 0028
> 0029
> 002A
What you seem to have here is an unvacuumed reference to an old
transaction number. If you've been vacuuming this database regularly
then I'm not sure how that could have happened. There is a post-7.2.1
clog bug fix that could cause premature removal of clog segments, but
it could only trigger after you've had more than 2 billion transactions
which you evidently haven't.
Fortunately, the problem seems to be in pg_statistic which is surely
non-critical data. I'd suggest a quick "DELETE FROM pg_statistic"
and then try to VACUUM pg_statistic. (If that doesn't work, you'll
have to try "TRUNCATE pg_statistic" instead but the delete would be
safer.) Once you can vacuum pg_statistic, a database-wide ANALYZE
will rebuild its contents.
regards, tom lane