Re: POC: make mxidoff 64 bits

On Thu, 4 Dec 2025 at 13:39, Heikki Linnakangas <hlinnaka(at)iki(dot)fi> wrote:

> However, that doesn't hold for pg_upgrade. pg_upgrade will try to read
> all the multixids. So we need to make the multixact reading code
> tolerant of the situations that could be present after a crash. I think
> the right philosophy here is that we try to read all the old multixids,
> and do our best to interpret them the same way that the old server
> would.

Something like attached?

Now previous scheme of upgrade with the bytes joggling start
looking not so bad. Just a funny thought that came to my mind.

Perhaps we should check that all the files exist and have the correct

sizes in the pre-check stage

Not sure about it. Because SLRU does not support "holes", simply
checking if the first and last multixacts exist will be enough. But
we'll do it anyway in a real conversion.

PFA to start a conversation.

--
Best regards,
Maxim Orlov.