Re: [PATCH]-hash index improving

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 <simon@2ndquadrant.com> wrote:
>
> On Fri, 2008-07-18 at 11:07 +0100, Gregory Stark wrote:
>> "Simon Riggs" <simon@2ndquadrant.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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