On Wed, Apr 30, 2014 at 5:55 AM, k...@rice.edu <k...@rice.edu> wrote: > I do not think that CPU costs matter as much as the O(1) probe to > get a result value specifically for very large indexes/tables where > even caching the upper levels of a B-tree index would kill your > working set in memory. I know, I know, everyone has so much memory > and can just buy more... but this does matter.
Have you actually investigated how little memory it takes to store the inner pages? It's typically less than 1% of the entire index. AFAIK, hash indexes are not used much in any other system. I think MySQL has them, and SQL Server 2014 has special in-memory hash table indexes for in memory tables, but that's all I can find on Google. -- Peter Geoghegan -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
