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From Mark Miller <>
Subject Re: custom similarity based on tf but greater than 1.0
Date Fri, 19 Jan 2007 00:59:44 GMT
Dont return 1 for tf...just return the tf straight with no 
changes...return freq. For everything else return 1. After that 
OMIT_NORMS should work. If you want to try a custom reader:

public class FakeNormsIndexReader extends FilterIndexReader {
    byte[] ones = SegmentReader.createFakeNorms(maxDoc());

    public FakeNormsIndexReader(IndexReader in) {
    public synchronized byte[] norms(String field) throws IOException {
          System.out.println("returning fake norms...");
        return ones;

    public synchronized void norms(String field, byte[] result, int 
offset) {
          System.out.println("writing fake norms...");
        System.arraycopy(ones, 0, result, offset, maxDoc());

The beauty of this reader is that you can flip between it and your 
custom similarity and Lucene's default implementations live on the same 

- Mark

Vagelis Kotsonis wrote:
> I feel kind of stupid...I don't get what hossman says in his post.
> I got the thing abou the OMMIT_NORMS and I tried to do it by calling
> Field.setOmitNorms(true); before adding a field in the index. After that I
> re-indexed my collection but still not making any difference.
> Tell me if I got it right. The second solution that you followed is building
> a custom FilteredIndexReader and implement these 2 functions :
> byte[] norms(String field)
> void norms(String field, byte[] result, int offset)
> Did I  get it right?
> Thank you and excuse me for continuously asking the same thing.
> Vagelis
> markrmiller wrote:
>> Sorry your having trouble find it! Allow 
>> Prob doesn't have great keyword for finding it. That should get you 
>> going though. Let me know if you have any questions.
>> - Mark

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