Re: SIGSEGV when trying to start in single user mode

=?UTF-8?B?QmrDtnJuIEjDpHVzZXI=?= <bjoernhaeuser(at)googlemail(dot)com> writes:
> I have a problem with my PostgreSQL 8.3.4 installation.

> We had some problems with our storage subsystem and it seems
> postgresql suffered a little bit from it.
> Here are some log excerpts:

> # /etc/init.d/postgresql-8.3 start
> Starting PostgreSQL 8.3 database server: main* Removed stale pid file.

You really need to get rid of that startup script, or at least get rid
of the part of it that thinks it should remove the postmaster's PID
file. That's completely unsafe and poor practice. (I doubt it's
related to your immediate problem, though.)

> 2009-09-19 16:51:00 CEST PANIC: right sibling's left-link doesn't
> match: block 49696 links to 49978 instead of expected 3 in index
> "132010"
> 2009-09-19 16:51:00 CEST LOG: startup process (PID 3727) was
> terminated by signal 6: Aborted

Ugh, so you have a corrupted index that is touched by the unreplayed
WAL sequence. I'm afraid the only easy way out of this is to use
pg_resetxlog, which is a bit risky since you'll lose whatever other
changes haven't been applied to the database. Probably the safest
thing to do is pg_resetxlog, start up, dump everything, initdb,
reload.

> But when I tried to start Postgresql in single-user mode to be able to
> repair this index i am getting the mentioned SIGSEGV.

Hmm, that's a bug, but even if it weren't broken it would not help you.
A single-user backend still has to replay any unreplayed WAL, so it
would still hit the PANIC.

regards, tom lane