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From Mark Miller <>
Subject Re: Time of processing hits.doc()
Date Sun, 18 Nov 2007 23:16:24 GMT
Correction: that issue to watch out for is in regards to the TopDocs 
HitCollector. If you where to go with your own HitCollector rather than 
TopDocs you might not necessarily have this problem (or at the least you 
can code around it).

Mark Miller wrote:
> Hey Haroldo.
> First thing you need to do is *stop* using Hits in your searches. Hits 
> is optimized for some pretty specific use cases and you will get along 
> much better by using a HitCollector.
> Hits has three main functions:
> It caches documents, normalizes scores, and stores ids associated with 
> scores (a HitDoc). If you attempt to retrieve a HitDoc past the first 
> 100 from Hits, a new search will be issued to grab double the required 
> HitDocs needed to satisfy your HitDoc retrieval attempt. This will be 
> repeated everytime you ask for a HitDoc beyond the current cache 
> (which began at 100). This means that if you need to get a HitDoc 
> beyond 100, Hits is not a great choice for you. You will want to use 
> the HitCollector instead...but remember that you are losing the 
> normalized scores (simple to copy code if you still want it) and the 
> document caching (I rarely want that anyway).
> An issue to watch out for: with Hits, you do not have to ask for how 
> many docs to get back, but with a HitCollector solution you will need 
> to. This is a minor dilema if you want to go over all of the hits no 
> matter what. You can pass a huge number to ensure you get everything, 
> but you will be creating large data structures if you do this, as 
> structure sizes may be initialized by the number you pass. Also, 
> passing the maximum integer will cause an error (negative init size) 
> as Lucene initializes a data structure to hold the hits as n+1.
> - Mark
> Haroldo Nascimento wrote:
>> I have a problem of performance when I need group the result do search
>> I have the code below:
>>    for (int i = 0; i < hits.length(); i++) {
>>                     doc = hits.doc(i);
>>                     obj1 = doc.get(Constants.STATE_DESC_FIELD_LABEL);
>>                     obj2 = doc.get(xxx);
>>                     ...
>>    }
>>   I work with volume of data very big. The search process in 0.300
>> seconds but when the object hits have much results, the time for get
>> all objects is very big. The command hits.doc(i) is processed in 2
>> second.
>>   Por exemplo. For hits.length() equals the 25.000 results, the time
>> of "pos search" is 7 seconds.
>>   I get all result because I need group the result (remove the
>> duplicate results).
>>   Is there any form in Lucene that group the result. I need of
>> anything as the command "group by" of sql.
>>   Thanks.
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