On Fri, Jan 13, 2012 at 12:18 PM, Simon Riggs <si...@2ndquadrant.com> wrote: > On Fri, Jan 13, 2012 at 5:08 PM, Robert Haas <robertmh...@gmail.com> wrote: >> Also, what happens if an all-visible bit gets set on the standby >> through some other mechanism - e.g. restored from an FPI or >> XLOG_HEAP_NEWPAGE? I'm not sure whether we ever do an FPI of the >> visibility map page itself, but we certainly do it for the heap pages. >> So it might be that this infrastructure would (somewhat bizarrely) >> trust the visibility map bits but not the PD_ALL_VISIBLE bits. I'm >> hoping Heikki or Tom will comment on this thread, because I think >> there are a bunch of subtle issues here and that we could easily screw >> it up by trying to plow through the problem too hastily. > > An FPI can't change the all visible flag. If it did, it would imply > that we'd skipped generation or replay of an XLOG_HEAP2_VISIBLE > record, or that we're doing crash recovery/inital startup and HS is > not yet enabled.
Interesting. I hadn't considered that point. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
