backing up corrupt database

On Wednesday 30 Oct 2002 3:56 pm, terry@ashtonwoodshomes.com wrote:

My first post didn't work, so here goes again

I want to backup my database, which appears to be corrupt. The projects
table is corrupt:
bash$ pg_dump devtest2
pg_dump: Attempt to lock table "projects" failed. ERROR: cannot find
attribute
8 of relation projects

When I try to drop this corrupted table:
devtest2=# drop table projects;
ERROR: cannot find attribute 8 of relation projects

How can I manually purge this table from the system tables so that I can
run a backup and then recreate the database?

Well, pg_class contains the tables - relname holds the name. I've just tried
deleting a table from it and using pg_dump and it seemed to work.

Having said that, I'd be tempted to pg_dump all the other tables individually
and then give it a go - I'm always a little uneasy about tinkering with the
system tables even when the developers say it should be fine.

--
Richard Huxton

<terry@ashtonwoodshomes.com> writes:

When I try to drop this corrupted table:
devtest2=# drop table projects;
ERROR: cannot find attribute 8 of relation projects

Sounds like a mess. What PG version is this? Do you know what happened
to cause the corruption?

How can I manually purge this table from the system tables so that I can run
a backup and then recreate the database?

If you do not care about this table, then "DELETE FROM pg_class WHERE
relname = 'projects'" would do it.

If you do care, I'd try a system-table reindex (read the REINDEX man
page carefully) before giving up on it. The problem is probably just
corruption in one of the indexes on pg_attribute.

regards, tom lane