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From Andrzej Bialecki ...@getopt.org>
Subject Re: IndexOptimizer (Re: Lucene performance bottlenecks)
Date Tue, 13 Dec 2005 14:43:00 GMT
Doug Cutting wrote:

> Andrzej Bialecki wrote:
>
>> Shouldn't this be combined with a HitCollector that collects only the 
>> first-n matches? Otherwise we still need to scan the whole posting 
>> list...
>
>
> Yes.  I was just posting the work-in-progress.


Ok, I just tested IndexSorter for now. It appears to work correctly, at 
least I get exactly the same results, with the same scores and the same 
explanations, if I run the smae queries on the original and on the 
sorted index. For now, the query response time is identical as far as I 
can tell.

> We will also need to estimate the total number of matches by 
> extrapolating linearly from the maximum doc id processed.


...which should be reported by the custom HitCollector, right?

> Finally, it is probably rather slow for large indexes, whose .fdt 
> won't fit in memory.  A simple way to improve that might be to use 
> Similarity.floatToByte-encoded floats when sorting (e.g., the norm 
> from an untokenized field) so that 


Yes, for an index that was 5 mln docs the IndexOptimizer takes ~10 min. 
to complete, this IndexSorter took over 1 hour...

-- 
Best regards,
Andrzej Bialecki     <><
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