Re: snapshot too old issues, first around wraparound and then more.
Peter Geoghegan <pg@bowt.ie>
From: Peter Geoghegan <pg@bowt.ie>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Andres Freund <andres@anarazel.de>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>,
Kevin Grittner <kgrittn@gmail.com>
Date: 2020-04-01T18:04:43Z
Lists: pgsql-hackers
On Wed, Apr 1, 2020 at 10:28 AM Robert Haas <robertmhaas@gmail.com> wrote: > Sure, but not all levels of risk are equal. Jumping out of a plane > carries some risk of death whether or not you have a parachute, but > that does not mean that we shouldn't worry about whether you have one > or not before you jump. > > In this case, I think it is pretty clear that hard-disabling the > feature by always setting old_snapshot_threshold to -1 carries less > risk of breaking unrelated things than removing code that caters to > the feature all over the code base. Perhaps it is not quite as > dramatic as my parachute example, but I think it is pretty clear all > the same that one is a lot more likely to introduce new bugs than the > other. A carefully targeted modification of a few lines of code in 1 > file just about has to carry less risk than ~1k lines of code spread > across 40 or so files. Yeah, that's certainly true. But is that fine point really what anybody disagrees about? I didn't think that Andres was focussed on literally ripping it out over just disabling it. > Is there any chance that you're planning to look into the details? > That would certainly be welcome from my perspective. I had a few other things that I was going to work on this week, but those seems less urgent. I'll take a look into it, and report back what I find. -- Peter Geoghegan
Commits
-
Remove the "snapshot too old" feature.
- f691f5b80a85 17.0 landed
-
Improve timeout.c's handling of repeated timeout set/cancel.
- 09cf1d522676 14.0 cited
-
Fix two bugs in MaintainOldSnapshotTimeMapping.
- 55b7e2f4d78d 14.0 cited