On Wed, Apr 20, 2011 at 3:35 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> System indexes really
> shouldn't be that much different from ordinary indexes. The property
> we actually are relying on is that there can't be any HOT chains that
> break the index, because it existed before any updates could have
> happened. I think the new approach is a more direct implementation of
> that concept than the original.
The problem was caused by a recursive update to pg_index. We need to
somehow ensure that update doesn't happen. We can either rely on this
subtle property we've established is true today but depends on lots of
fiddly bits of behaviour throughout the system or we can insert a line
saying "just don't do that".
I suppose it doesn't matter as long as there are the new assertion
checks (perhaps they should be elog()s. Since if it ever happens at
least we won't corrupt the database and we'll detect that the logic no
longer holds.
--
greg