Well, I'll do it after I finish my second patch. Hash index should be more efficient than btree when N is big enough. It seems meaningful to find how big N is in an experiment way.
On Fri, Jul 18, 2008 at 6:35 PM, Simon Riggs <[EMAIL PROTECTED]> wrote: > > On Fri, 2008-07-18 at 11:07 +0100, Gregory Stark wrote: >> "Simon Riggs" <[EMAIL PROTECTED]> writes: > >> hash lookups can in theory be O(1). > > I'm not sure whether that applies here? I'm interested in how *this* > patch will work, not in more generic algorithm theory. > > To patch authors: Can we please see a table showing expected number of > logical I/Os (i,e, block accesses) for btrees and hash indexes > > e.g. for 100-byte rows... > > rows btree hash > ---- ----- ---- > 10^2 > 10^3 > 10^4 > 10^5 > 10^6 > 10^7 > 10^8 > > -- > Simon Riggs www.2ndQuadrant.com > PostgreSQL Training, Services and Support > > -- Best Regards, Xiao Meng DKERC, Harbin Institute of Technology, China Gtalk: [EMAIL PROTECTED] MSN: [EMAIL PROTECTED] http://xiaomeng.yo2.cn -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
