Re: Unable to drop index

Oliver Duke-Williams <o(dot)w(dot)duke-williams(at)leeds(dot)ac(dot)uk> writes:
> The table on which the index was built is no longer present (it should
> have been dropped by my application after being used), but it would
> appear that the index was not dropped at the same time as the table:

That's fairly strange; it should be impossible, in fact, because of the
pg_depend mechanism.

> drop index iext_41827440000_24 ;
> ERROR: could not open relation with OID 147483811

> Looking in pg_class for an entry with this OID (147483811) returns 0
> rows; an entry exists in pg_class for the index itself.

What is the OID of the index itself? Are there any rows in pg_depend
matching either the index OID or 147483811 in either objid or refobjid?
How about pg_index (see indexrelid and indrelid respectively)? How
about pg_attribute (see attrelid)? Is the underlying file (named by
pg_class.relfilenode) still there?

> How can I safely remove the index? The old copy of the index is
> preventing the creation of a new table and associated index of the same
> names.

You can probably just "rm" the underlying file and DELETE the pg_class
row plus any other rows you found above. However I wonder what other
corruption may have occurred in whatever event produced this situation.
I'm thinking you might have lost a whole page of pg_class, for example.
It'd likely be a good idea to see if you can pg_dump and reload the
database.

regards, tom lane