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Subject: Re: Two-Tier Hashtable vs. One-Tier

Author: martin fierz

Date: 02:10:56 09/22/04

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On September 21, 2004 at 17:36:47, Stuart Cracraft wrote:

>Hi -- this past weekend I switched from single-tier replace
>always to two-tier place 1st tier in 2nd if incoming position
>is searched to a >= depth than currently stored at hash entry
>and store incoming position in 1st tier, otherwise always replace
>2nd tier if depth is.
[snip]

i use only one hashtable in my program. whenever i tried using 2 tables, my
results were worse. i tried this many times, because everybody here says it's
better to use 2 tables. i never got it working, and decided to stick with 1
table, as it is much simpler overall.

IIRC dieter buerssner also mentioned that for him 1 table worked just as well as
2 tables.

as others have said, if you want to benchmark this you'll have to use longer
searches - and to do that you should use a different test than WAC, i suggest
using ECMGCP, that is much tougher and more suited for longer searches. you
could also artificially create lots of replacements by making the hashtable(s)
really small - but i'm not sure that that will give you a relevant result...

cheers
  martin



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