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From Paul Elschot <>
Subject Re: Performance problem, Search within search for TopDocs ?
Date Thu, 25 Aug 2005 07:49:31 GMT
On Thursday 25 August 2005 09:14, WolfgangTäger wrote:
> Hello Paul, hello Doug,
> many thanks for your help !!
> @Paul: I didn't try your method, Paul, because I feared that retrieving 
> all hits would not solve my problems, because the number of hits may be 
> many times higher than the 2000 I wanted for my statistics.
> @Doug: I tried your method which is extremely fast !
> The first run is still very slow (many seconds, but this is not a problem 
> for me), measuring the following ones sometimes gives 0ms  using 
> currentTimeMillis() !!

The method I gave is to try to optimize the first reading from disk.
I'd expect FieldCache to use it.

> Now I have one more question: I want to use the TopDocs result 
> TopDocs hits =, (Filter)null, 2000);
> as a filter for following queries like
> DE:Schlüssel            limited to the 2000 TopDocs for the query "key"
> AFAIK, the recommended way for search within a search is:
> Combine the previous query with the current query using BooleanQuery, 
> wherein the previous query is marked as required.
> Can this be done in this case ? My query does not contain any information 
> that I want 2000 results as maximum.
> Note: I do not want to limit the combined query to 2000, but typically I 
> expect fewer results by first restricting the "key" query to 2000 and then 
> looking in the results for DE:"Schlüssel".

Have a look at QueryFilter and FilteredQuery, they fit nicely here.

Paul Elschot

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