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Transposition Table Usage ratio

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Hi everybody, I am doing a Alpha Beta Search and I am using a Transposition table of size 2^20=1.000.000. When I am searching 15.000.000 nodes, the Table is never been used more than 55% (it often is under 15%). I am using Zobrist Keys as described here http://www.seanet.com/~brucemo/topics/zobrist.htm to store my positions in the table. I feel, that this is not much. Am I correct? Any advise? I know, without me posting code you can not give me advice, but I am not sure what to post ...

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That definitely looks low. I would expect pretty much 100% coverage after 15 million nodes.

Try to see if there is a pattern of what entries end up full and which end up empty.

I don't think there is much you can post that would be useful.

And good luck!

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Hello
Thanks for your answer alvaro.
How would I search for patterns? I collected some data: Because I am not recording the in the hash table on rest_search_depth==0 but still counting the nodes, I am calling "StorePositionInHashTable" much less than 17.000.000 times. Still some strange numbers:
223.733 times I write into a field, which is empty.
34.822 times I overwrite a field with a different position.
1.895.399 times I do not store the position because another position is with a bigger depth is already stored here.

So at a total, "StorePositionInHashTable" is called about 2.000.000 times. After this, the table is filled by 223.733/2^20 * 100 = 21%. Not a good result :(.

I do not know what to do. Looking at this numbers, any advise? Thanks!

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