Mark Rostron wrote:
What is the procedure that postgres uses to decide whether or not a table/index block will be left in the shared_buffers cache at the end of the operation?
There is no such procedure. When a table or index page is used, its usage count goes up, which means it's more likely to stay in the cache for longer afterwards. Processing trying to allocate pages are constantly circling the buffer cache looking for pages where the usage count is at 0 to re-use. The only special cases are for sequential scans and VACUUM, which use continuously re-use a small section of the buffer cache in some cases instead.
-- Greg Smith 2ndQuadrant US greg@xxxxxxxxxxxxxxx Baltimore, MD PostgreSQL Training, Services and Support www.2ndQuadrant.us "PostgreSQL 9.0 High Performance": http://www.2ndQuadrant.com/books -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
