Hi Sriram,
I don't see any obvious mistakes, although you don't need to create a
FilteredQuery: There are plenty of search-methods on the IndexSearcher
that accept both a query (your TermQuery) and a filter (your TermsFilter).
The way I understand Filters (but I have no advanced in-depth knowledge
of them) is that they are very similar to Queries.
Queries are used for two tasks; matching a item and giving some measure
of how "well" it matched (i.e. the score).
Filters are used only for matching, but I doubt there is very much
difference from a technical point of view between the to ways of
matching items.
I'll leave more detailed explanations to others, as I might make too
many mistakes or just assume I know something I actually don't :)
Best regards,
Arjen
On 25-7-2013 19:56 Sriram Sankar wrote:
Thanks everyone. I'm trying this out:
So searching would become:
- Create a Query with only your termA
- Create a TermsFilter with all your termB's
- execute your preferred search-method with both the query and the filter
I don't the get the same results as before - and am still debugging. But
I'm including before and after code in case someone is able to see a
problem with what I'm doing.
I'm also looking for docs on how filters work (or will read the code). But
at a high level, is the filter fully created when the Filter object is
created? Or is it incrementally built during traversal (when next() and
advance() are called on the filters). Reason for this question is related
to early termination.
The two versions of code (query based and filter based) are shown below -
let me know if you see a problem with either. Ignore any minor syntactic
errors that may have got introduced as I simplified my code for inclusion
here.
Thanks,
Sriram.
QUERY APPROACH:
BooleanQuery orTerms = new BooleanQuery();
for (int i = 0; i < orCount; ++i) {
TermQuery orArg = new TermQuery(new Term("conn",
Integer.toString(connection[i])));
BooleanClause cl = new BooleanClause(orArg, BooleanClause.Occur.SHOULD);
orTerms.add(cl);
}
TermQuery tq = new TermQuery(new Term("name", name));
BooleanQuery query = new BooleanQuery();
query.add(new BooleanClause(tq, BooleanClause.Occur.MUST));
query.add(new BooleanClause(orTerms, BooleanClause.Occur.MUST));
FILTER APPROACH:
List<Term> orTerms = new ArrayList<Term>();
for (int i = 0; i < orCount; ++i) {
terms.add(new Term("conn",
Integer.toString(connection[i])));
}
TermsFilter conns = new TermsFilter(terms);
TermQuery tq = new TermQuery(new Term("name", name));
FilteredQuery query = new FilteredQuery(tq, conns);
On Thu, Jul 25, 2013 at 12:14 AM, Arjen van der Meijden <
acmmail...@tweakers.net> wrote:
On 24-7-2013 21:58 Sriram Sankar wrote:
On Wed, Jul 24, 2013 at 10:24 AM, Jack Krupansky <j...@basetechnology.com
**wrote:
Scoring has been a major focus of Lucene. Non-scored filters are also
available, but the query parsers are focused (exclusively) on
scored-search.
When you say "filter" do you mean a step performed after retrieval? Or is
it yet another retrieval operation?
He is really referring to the Filters available as an addition to
retrieval. The ones you supply with the search-method:
http://lucene.apache.org/core/**4_4_0/core/org/apache/lucene/**
search/IndexSearcher.html#**search%28org.apache.lucene.**
search.Query,%20org.apache.**lucene.search.Filter,%20int%29<http://lucene.apache.org/core/4_4_0/core/org/apache/lucene/search/IndexSearcher.html#search%28org.apache.lucene.search.Query,%20org.apache.lucene.search.Filter,%20int%29>
Unfortunately the documentation of Lucene is a bit fragmented, but
basically they limit the scope of your search domain (i.e. reduce the
available set of documents) during the processing of a query. So it
basically becomes (query) AND (filters).
There are several useful implementations available for the filters. But in
your case you can just create a single TermsFilter (its in the queries
module/package) which is simply a OR-list like the one in your example
(similar to a basic IN in sql):
http://lucene.apache.org/core/**4_4_0/queries/org/apache/**
lucene/queries/TermsFilter.**html<http://lucene.apache.org/core/4_4_0/queries/org/apache/lucene/queries/TermsFilter.html>
So searching would become:
- Create a Query with only your termA
- Create a TermsFilter with all your termB's
- execute your preferred search-method with both the query and the filter
If you where interested in the scores of each result, this would not work
too well since all scores will only be based on the query that only
contains termA... But since you don't care about that, this should be get
you a big performance gain.
Best regards,
Arjen
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