On Mon, Jun 4, 2012 at 9:26 PM, Jeff Davis <pg...@j-davis.com> wrote: > Thoughts?
Simon already proposed a way of doing this that doesn't require explicit user action, which seems preferable to a method that does require explicit user action, even though it's a little harder to implement. His idea was to store the XID of the process creating the table in the pg_class row, which I think is *probably* better than your idea of having a process that waits and then flips the flag. There are some finicky details though - see previous thread for discussion of some of the issues. It would be very nice to have a method that detects whether or not there is only one open snapshot in a particular backend. Any time that condition is met, tuples written into a table created or truncated in the current transaction can be written with HEAP_XMIN_COMMITTED already set. That is not as nice as being able to set HEAP_XMIN_COMMITTED *and* PD_ALL_VISIBLE *and* the visibility map, but it would still be a big improvement over the status quo. I would like to see us get that part done and committed and then worry about writing the tuples with PD_ALL_VISIBLE set as a separate project. In many cases it would also be nice to write the tuples pre-frozen, so I think we should look for a design that will support that. -- 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
