On 02/25/2018 03:57 PM, Magnus Hagander wrote: > > ... > >> > I very strongly doubg it's a "very noticeable operational problem". People >> > > don't restart their databases very often... Let's say it takes 2-3 weeks >> > to >> > > complete a run in a fairly large database. How many such large databases >> > > actually restart that frequently? I'm not sure I know of any. And the >> > only >> > > effect of it is you have to start the process over (but read-only for the >> > > part you have already done). It's certainly not ideal, but I don't agree >> > > it's in any form a "very noticeable problem". >> > >> > I definitely know large databases that fail over more frequently than >> > that. >> > >> >> I would argue that they have bigger issues than enabling checksums... By >> far. > > In one case it's intentional, to make sure the overall system copes. Not > that insane. > > That I can understand. But in a scenario like that, you can also stop > doing that for the period of time when you're rebuilding checksums, if > re-reading the database over and over again is an issue. > > Note, I'm not saying it wouldn't be nice to have the incremental > functionality. I'm just saying it's not needed in a first version. >
I agree with this sentiment. I don't think we can make each patch perfect for everyone - certainly not in v1 :-/ Sure, it would be great to allow resume after a restart, but if that means we won't get anything in PG 11 then I think it's not a good service to our users. OTOH if the patch without a resume addresses the issue for 99% of users, and we can improve it in PG 12, why not? That seems exactly like the incremental thing we do for many other features. So +1 to not make the "incremental resume" mandatory. If we can support it, great! But I think the patch may seem less complex than it actually is, and figuring out how the resume should work will take some time. regards -- Tomas Vondra http://www.2ndQuadrant.com PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
