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From Emmanuel Lecharny <>
Subject Re: Searching takes unrealistic time.
Date Fri, 25 Jan 2008 16:22:23 GMT
Siva Kumar wrote:
> Thank you for the tip Emmanuel.
You're welcomed, Siva
> But its not seem to help me.
May be because the cache size you selected is far from being large enough.

Let me explain.

Suppose that disk access are 100 times slower than memory access. If it 
cost T to reach data from disk, with 40 000 elements, if you cache 100 
of them, then you will have a ratio of 100/40000 access done in T/100 
and 39900/40000 access done in T.
Average access time = (39900/40000*T + 100/4000000*(T/100)) = 99,7525% T 
(~ T, in other terms).

Now, you have a 5000 cache size. What does it means in term of 
performance increase ?

5000/40000 access done in T/100
35000/40000 access done in T

Average : (5000/40000*T/100 + 35000/40000*T) = 87,625% T. In other 
terms, roughly  a 10% speedup. Almost unnoticeable...

Do what I said : set the cache size to 40000, increase your JVM memory .

PS : You can also increase the cachesize for entries ( the cachesize 
parameter associated with your partition, not those associated with index).

Hope it helps...

cordialement, regards,
Emmanuel L├ęcharny

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