Koichi Suzuki <koichi....@gmail.com> writes: > Please find enclosed 2nd patch of pg_readahead which include a patch > to bufer manager to skip prefetch of pages already in shared buffer.
I'm a bit confused by this comment. PrefetchBuffer already checks if the page is in shared buffers. What is tricky to avoid is prefetching the same page twice -- since the first prefetch doesn't actually put it in shared buffers there's no way to avoid prefetching it again unless you keep some kind of hash of recently prefetched buffers. For the index scan case I'm debating about whether to add such a cache directly to PrefetchBuffer -- in which case it would remember if some other scan prefetched the same buffer -- or to keep it in the index scan code. -- Gregory Stark EnterpriseDB http://www.enterprisedb.com Ask me about EnterpriseDB's On-Demand Production Tuning -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
