Re: POC: make mxidoff 64 bits - Mailing list pgsql-hackers

From Maxim Orlov
Subject Re: POC: make mxidoff 64 bits
Date
Msg-id CACG=eza-JrdrWqCu2zR05+jWPSHO2CO9hrHTYBNF9LSd4dzXGw@mail.gmail.com
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In response to Re: POC: make mxidoff 64 bits  (Heikki Linnakangas <hlinnaka@iki.fi>)
List pgsql-hackers

On Thu, 4 Dec 2025 at 13:39, Heikki Linnakangas <hlinnaka@iki.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.
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