Re: Why not try for a HOT update, even when PageIsFull()?
Peter Geoghegan <pg@bowt.ie>
From: Peter Geoghegan <pg@bowt.ie>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Pavan Deolasee <pavan.deolasee@gmail.com>
Date: 2021-11-22T00:29:11Z
Lists: pgsql-hackers
On Fri, Nov 19, 2021 at 11:51 AM Alvaro Herrera <alvherre@alvh.no-ip.org> wrote: > Hmm, I don't have any memory of introducing this; and if you look at the > thread, you'll notice that it got there between the first patch I posted > and the second one, without any mention of the reason. I probably got > that code from the WARM patch series at some point, thinking that it was > an obvious optimization; but I'm fairly certain that we didn't run any > tailored micro-benchmark to justify it. I suspected that it was something like that. I agree that it's unlikely that we'll be able to do another HOT update for as long as the page has PD_PAGE_FULL set. But that's not saying much; it's also unlikely that heap_update will find that PD_PAGE_FULL is set to begin with. And, the chances of successfully applying HOT again are workload dependent. > I certainly do not object to removing it. I'd like to do so soon. I'll wait a few more days, in case Pavan objects. Thanks -- Peter Geoghegan
Commits
-
Go back to considering HOT on pages marked full.
- 1a6f5a0e8763 15.0 landed
-
Avoid improbable PANIC during heap_update.
- 34f581c39e97 14.0 cited
-
Remove tupgone special case from vacuumlazy.c.
- 8523492d4e34 14.0 cited
-
Simplify check of modified attributes in heap_update
- 2fd8685e7fd9 10.0 cited