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Subject: Re: Hash Table

Author: Robert Hyatt

Date: 18:39:31 01/19/98

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On January 19, 1998 at 19:11:38, Stuart Cracraft wrote:

>On January 19, 1998 at 17:37:34, Robert Hyatt wrote:
>
>>On January 19, 1998 at 17:09:00, Stuart Cracraft wrote:
>>
>>>What is the typical hash table successful percentage retrieve value?
>>>
>>>I'm looking for this number for at least one other program for a
>>>typical search or group of searches:
>>>
>>>	found-in-hashtable * 100
>>>	------------------------
>>>      total attempts to probe hashtable
>>>
>>>--Stuart
>>
>>
>>Depends on what you are counting, and the position you are searching.
>>
>>If you are simply counting positions where the hash signature matches
>>what is in the table, you should get 25% and higher.  If you are
>>counting
>>positions where the hash table hit actually stops the search early due
>>to
>>a fail high/low or exact score match, this should be around 10% and get
>>better as depth increases.
>
>I assume your 25% case reflects that the called-depth >= stored-depth
>for the store-entry case and stored-depth < called-depth for the
>retrieve-entry
>case where stored-depth is the depth currently in the hash table and
>called-depth is the depth supplied to the store-entry/retrieve-entry
>routines.
>
>--Stuart

it applies to *all* probes attempted.  If the keys match, they count in
the 25%.  But not all such positions are useful.  Useful hits is in the
10%
range for early middlegame...



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