Re: Remove remnants of "snapshot too old" - Mailing list pgsql-hackers

From Nathan Bossart
Subject Re: Remove remnants of "snapshot too old"
Date
Msg-id Z1CE7pO3Lkrhqdhk@nathan
Whole thread Raw
In response to Re: Remove remnants of "snapshot too old"  (Andres Freund <andres@anarazel.de>)
List pgsql-hackers
On Wed, Dec 04, 2024 at 09:55:43AM +0200, Heikki Linnakangas wrote:
> On 04/12/2024 03:24, Tom Lane wrote:
>> Andres Freund <andres@anarazel.de> writes:
>> > Most of this I agree with. But I'm not sure just removing the toast snapshot
>> > stuff is good - we've had a bunch of bugs where we don't hold a snapshot for
>> > long enough to actually ensure that toast tuples stay alive.
>> 
>> Yeah, the stuff concerned with toast snapshots has nothing to do
>> with that old user-visible feature.  It's to keep us from writing
>> incorrect code, and it's still (very) needed.
> 
> Right. Here's a new attempt that keeps that check.

Looks reasonable to me.  One idea I had is to make SnapshotToast a macro
that first does an AssertMacro(HaveRegisteredOrActiveSnapshot()), but the
approach in the patch seems fine, too.

-- 
nathan



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