On 15 October 2012 18:07, Robert Haas <robertmh...@gmail.com> wrote: > On Mon, Oct 15, 2012 at 12:59 PM, Simon Riggs <si...@2ndquadrant.com> wrote: >>> I don't think I'd go so far as to say that we should >>> imply that they'll be removed in a future release. Given how deeply >>> intertwined they are with the planner, I doubt that that will happen; >>> and I think there is enough interest in the technology that it's >>> likely to eventually be fixed. >> >> Hash indexes aren't used in the planner. Hash joins use completely >> separate code. > > It's not really completely separate, because to do a hash join we have > to find a hash function for the relevant data types, and IIUC we do > that by looking up the default hash opclass for the datatype and > finding its first support function. Of course, if we were to remove > the hash AM, then you couldn't define a hash opclass against it.
Presumably it defaults to hash_any() but I get the picture. -- Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
