Hi list,
This is just to let you know that I found the reason (Dan sent me a
small sample index off-list), and I thought that the reason for this
error was obscure and tricky enough that you might be interested in the
solution.
The problem lied in custom boost values. It was impossible to find the
documents using the high-level search() interface. If you remember, this
interface skips the lowest-scoring hits, among others documents with
score==0 :-)
How can the score be 0 if the document matches (and it matched, because
it clearly contained the term from the query)? I implemented a version
of HitCollector that collects all hits, in order to investigate this.
Running a query "testField:test" against that sample index I got 1 hit
with score 0, and this explanation:
0.0000 fieldWeight(testField:test in 0), product of:
1.0000 tf(termFreq(testField:test)=1)
0.3069 idf(docFreq=1)
0.0000 fieldNorm(field=testField, doc=0)
Under normal circumstances fieldNorm is never 0 ... unless a boosting
has been applied. In this case the original poster didn't apply boost=0,
but some other (small) value. Boost values are encoded floats with very
coarse resolution. In this case this resulted in fieldNorm falling below
resolution of the encoded float. The fractional part was lost in this
case, because it was too small to be encoded, so that the fieldNorm
became 0. As a consequence, the score became 0 too, even though the
document matched ...
--
Best regards,
Andrzej Bialecki <><
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