Gregory Stark wrote:
For i/o-bound databases with very large indexes there should be an opportunity where btree lookups are O(logn) and hash lookups can in theory be O(1).
Ignoring the big-O complexity, if a hash index only stores a 32-bit hash code instead of the whole key, it could be a big win in storage size, and therefore in cache-efficiency and performance, when the keys are very long.
Granted, it's not very common to use a 1K text field as a key column... -- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
