Excerpts from Heikki Linnakangas's message of mié feb 29 16:09:02 -0300 2012: > On 29.02.2012 19:54, Simon Riggs wrote: > > I'm beginning to lose faith that objections are being raised at a > > rational level. It's not a panel game with points for clever answers, > > its an engineering debate about how to add features real users want. > > And they do want, so let me solve the problems by agreeing something > > early enough to allow it to be implemented, rather than just > > discussing it until we run out of time. > > I thought my view on how this should be done was already clear, but just > in case it isn't, let me restate: Enlarge the page header to make room > for the checksum. To handle upgrades, put code in the backend to change > the page format from old version to new one on-the-fly, as pages are > read in. Because we're making the header larger, we need to ensure that > there's room on every page. To do that, write a utility that you run on > the cluster before running pg_upgrade, which moves tuples to ensure > that. To ensure that the space doesn't get used again before upgrading, > change the old version so that it reserves those N bytes in all new > insertions and updates (I believe that approach has been discussed > before and everyone is comfortable with backpatching such a change). All > of this in 9.3.
Note that if we want such an utility to walk and transform pages, we probably need a marker in the catalogs somewhere so that pg_upgrade can make sure that it was done in all candidate tables -- which is something that we should get in 9.2 so that it can be used in 9.3. Such a marker would also allow us get rid of HEAP_MOVED_IN and HEAP_MOVED_OUT. -- Álvaro Herrera <alvhe...@commandprompt.com> The PostgreSQL Company - Command Prompt, Inc. PostgreSQL Replication, Consulting, Custom Development, 24x7 support -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
