On Fri, Jan 12, 2024 at 11:50 AM Peter Geoghegan <p...@bowt.ie> wrote: > Why do you think that lazy_scan_prune() and lazy_scan_noprune() have > different ideas about whether to update the FSM or not?
When lazy_scan_prune() is called, we call RecordPageWithFreeSpace if vacrel->nindexes == 0 && prunestate.has_lpdead_items. See the code near the comment that begins "Consider the need to do page-at-a-time heap vacuuming". When lazy_scan_noprune() is called, whether we call RecordPageWithFreeSpace depends on the output parameter recordfreespace. That is set to true whenever vacrel->nindexes == 0 || lpdead_items == 0. See the code near the comment that begins "Save any LP_DEAD items". The case where I thought there was a behavior difference is when vacrel->nindexes == 0 and lpdead_items == 0 and thus prunestate.has_lpdead_items is false. But now I see (from Melanie's email) that this isn't really true, because in that case we fall through to the logic that we use when indexes are present, giving us a second chance to call RecordPageWithFreeSpace(), which we take when (prunestate.has_lpdead_items && vacrel->do_index_vacuuming) comes out false, as it always does in the scenario that I postulated. P.S. to Melanie: I'll respond to your further emails next but I wanted to respond to this one from Peter first so he didn't think I was rudely ignoring him. :-) P.P.S. to everyone: Yikes, this logic is really confusing. -- Robert Haas EDB: http://www.enterprisedb.com
