Alvaro Herrera wrote:
Are you saying that an indexscan "Filter" only acts after getting the heap tuple? If that's the case, then there's room for optimization here, namely if the affected column is part of the index key, then we could do the filtering before fetching the heap tuple.
That's right. Yes, there's definitely room for optimization. In general, it seems we should detach the index scan and heap fetch more. Perhaps make them two different nodes, like the bitmap index scan and bitmap heap scan. It would allow us to do the above. It's also going to be necessary if we ever get to implement index-only scans.
-- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com
