Hi, On April 15, 2022 2:14:47 PM EDT, Tom Lane <t...@sss.pgh.pa.us> wrote: >Andres Freund <and...@anarazel.de> writes: >> On 2022-04-15 12:36:52 -0400, Tom Lane wrote: >>> Yeah, I was also thinking about a flag in PGPROC being a more reliable >>> way to do this. Is there anything besides walsenders that should set >>> that flag? > >> Not that I can think of. It's only because of hs_feedback that we need >> to. I guess it's possible that somebody build some extension that needs >> something similar, but then they'd need to set that flag... > >Here's a WIP patch for that. The only exciting thing in it is that >because of some undocumented cowboy programming in walsender.c, the > Assert((proc->statusFlags & (~PROC_COPYABLE_FLAGS)) == 0); >in ProcArrayInstallRestoredXmin fires unless we skip that. > >I could use some help filling in the XXX comments, because it's far >from clear to me *why* walsenders need this to happen.
I'm out for the rest of the day due to family events (visiting my girlfriend's parents till Wednesday), I can take a stab at formulating something after. If you want to commit before: The reason is that walsenders use their xmin to represent the xmin of standbys when using hot_standby_feedback. Since we're only transmitting global horizons up from standbys, it has to influence globally (and it would be hard to represent per db horizons anyway). Andres -- Sent from my Android device with K-9 Mail. Please excuse my brevity.
