| From: | Simon Riggs <simon(at)2ndquadrant(dot)com> |
|---|---|
| To: | Gregory Stark <stark(at)enterprisedb(dot)com> |
| Cc: | Dann Corbit <DCorbit(at)connx(dot)com>, "Jonah H(dot) Harris" <jonah(dot)harris(at)gmail(dot)com>, Xiao Meng <mx(dot)cogito(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org, Kenneth Marshall <ktm(at)rice(dot)edu> |
| Subject: | Re: [PATCH]-hash index improving |
| Date: | 2008-07-18 10:35:25 |
| Message-ID: | 1216377325.19656.770.camel@ebony.2ndQuadrant |
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| Lists: | pgsql-hackers |
On Fri, 2008-07-18 at 11:07 +0100, Gregory Stark wrote:
> "Simon Riggs" <simon(at)2ndquadrant(dot)com> 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
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