Re: Nasty btree deletion bug

Tom Lane wrote:
> On further reflection, I think I understand why we've not realized the
> existence of this bug before: in fact, it *doesn't* lead to wrong search
> answers.  I think the only visible consequence is exactly the "failed to
> re-find parent key" VACUUM error that Ed saw.  The reason is that the
> key misordering in the grandparent level is nearly harmless.  Using your
> example of

Yep. It's pretty harmless.

But now that I look at the original post by Ed, I don't see how the 
"failed to re-find parent key" error could result from the issue we've 
been talking about. The error message is printed when _bt_getstackbuf is 
unable to re-find an item in the parent of a deleted page, but 
_bt_getstackbuf doesn't look at or compare the keys at all.

--   Heikki Linnakangas  EnterpriseDB   http://www.enterprisedb.com