On 21/03/17 18:14, Robert Haas wrote: > On Tue, Mar 21, 2017 at 1:08 PM, Peter Geoghegan <p...@bowt.ie> wrote: >> On Tue, Mar 21, 2017 at 10:04 AM, Robert Haas <robertmh...@gmail.com> wrote: >>> I think that's a good question. I previously expressed similar >>> concerns. On the one hand, it's hard to ignore the fact that, in the >>> cases where this wins, it already buys us a lot of performance >>> improvement. On the other hand, as you say (and as I said), it eats >>> up a lot of bits, and that limits what we can do in the future. On >>> the one hand, there is a saying that a bird in the hand is worth two >>> in the bush. On the other hand, there is also a saying that one >>> should not paint oneself into the corner. >> >> Are we really saying that there can be no incompatible change to the >> on-disk representation for the rest of eternity? I can see why that's >> something to avoid indefinitely, but I wouldn't like to rule it out. > > Well, I don't want to rule it out either, but if we do a release to > which you can't pg_upgrade, it's going to be really painful for a lot > of users. Many users can't realistically upgrade using pg_dump, ever. > So they'll be stuck on the release before the one that breaks > compatibility for a very long time. >
This is why I like the idea of pluggable storage, if we ever get that it would buy us ability to implement completely different heap format without breaking pg_upgrade. -- Petr Jelinek http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
