On Tue, Mar 23, 2021 at 12:44 PM Tom Lane <t...@sss.pgh.pa.us> wrote: > > I will make this change to HEAD soon, barring objections. > > +1. Not deleting the upper page seems better than the alternatives.
FWIW it might also work that way as a holdover from the old page deletion algorithm. These days we decide exactly which pages (leaf page plus possible internal pages) are to be deleted as a whole up front (these are a subtree, though usually just a degenerate single-leaf-page subtree -- internal page deletions are rare). One of the advantages of this design is that we verify practically all of the work involved in deleting an entire subtree up-front, inside _bt_lock_subtree_parent(). It's clearly safe to back out of it if it looks dicey. -- Peter Geoghegan
