Jeff Davis wrote: > On Wed, 2007-08-15 at 11:54 -0400, Bruce Momjian wrote: > > I have added another idea for index-only scans to the TODO list: > > > > > A third idea would be for a heap scan to check if all rows are visible > > > and if so set a per-table flag which can be checked by index scans. > > > Any change to the table would have to clear the flag. To detect > > > changes during the heap scan a counter could be set at the start and > > > checked at the end --- if it is the same, the table has not been > > > modified --- any table change would increment the counter. > > This sounds useful for read-only or read-mostly tables.
I think it's too coarse-grained to be really useful. If it was one bit per page it could work, but one bit per relation is going to be reset too frequently. -- Alvaro Herrera http://www.CommandPrompt.com/ PostgreSQL Replication, Consulting, Custom Development, 24x7 support ---------------------------(end of broadcast)--------------------------- TIP 4: Have you searched our list archives? http://archives.postgresql.org
