Hi,
After a little digging/debugging, it seems to me that what I am seeing is
actually normal and expected behaviour. Morever, it seems that once a Field is
indexed without it being NO_NORMS field, it is not really possible to make it a
trully NO_NORMS field. From what I can tell, one of the key methods is in
DocumentWriter:
private final void writeNorms(String segment) throws IOException {
for(int n = 0; n < fieldInfos.size(); n++){
FieldInfo fi = fieldInfos.fieldInfo(n);
if(fi.isIndexed && !fi.omitNorms){
<== here
float norm = fieldBoosts[n] * similarity.lengthNorm(fi.name,
fieldLengths[n]);
IndexOutput norms = directory.createOutput(segment + ".f" + n);
try {
norms.writeByte(Similarity.encodeNorm(norm));
} finally {
norms.close();
}
}
}
}
This is where norms for a field are either written if the field is indexed and
*not* a NO_NORMS field, or not written if the field is indexed and *is* a
NO_NORMS field.
I also see this in the FieldInfo class:
if (fi.omitNorms != omitNorms) {
fi.omitNorms = false; // once norms are stored, always
store
}
Thus, it's not really possible to completely kill field norms and make the
field a genuine NO_NORMS field after the fact... is this correct?
Therefore, that FieldNormModifier call that tries to turn an existing field
into a NO_NORMS field doesn't really work:
reader.setNorm(d, fieldName, fakeNorms[0]); // this
is my case - turning existing fields into Field.NO_NORMS fields.
I think this just fakes out a norms file for a given field, and this norms file
ends up containing a byte[] of encoded 1.0f's, one for each Document. But this
really is completely fake - this just makes the norms be 1.0, while NO_NORMS
skips the *writing* of norms file for a given field completely.
Is the above correct?
If so, is there any way to turn an existing field into a genuine NO_NORMS field?
Thanks,
Otis
----- Original Message ----
From: Otis Gospodnetic <[EMAIL PROTECTED]>
To: java-user@lucene.apache.org
Sent: Tuesday, January 9, 2007 2:36:46 AM
Subject: .sN (separate norms files) and NO_NORMS
Hi,
I recently run the FieldNormModifier (see
http://issues.apache.org/jira/browse/LUCENE-741 ) on 8 fields that I wanted to
turn into NO_NORMS fields. I run this on several optimized .cfs indices.
Afterwards I noticed that *some* (but not all!) indices contained 8 .sN (where
N is a number) files. Those are norm files, I believe (Lucene 2.0.0).
Meanwhile, the .cfs file remained untouched. Does anyone know how to explain
this?
What bugs me is:
- Why was the original .cfs not modified?
- Why did .sN files show up separately?
What bugs my colleague (hi Brian!) is:
- Why are there separate norms for each NO_NORMS field, and not just 1 for all
of them?
(my answer is that the files still exists like they exist for non-NO_NORMS
fields, it's just that they are full of 1.0s, but I'm not absolutely sure
that's the correct answer.)
I would have expected the .cfs file to get modified. Or I'd expect to see 8
.sN files along the unmodified .cfs in *all* index directories I run this
against, and not just some.
The essential, index-modifying part of FieldNormModifier is this:
reader = IndexReader.open(dir);
for (int d = 0; d < termCounts.length; d++) {
if (! reader.isDeleted(d)) {
if (sim == null)
reader.setNorm(d, fieldName, fakeNorms[0]); // this is my
case - turning existing fields into Field.NO_NORMS fields.
else
reader.setNorm(d, fieldName,
sim.encodeNorm(sim.lengthNorm(fieldName, termCounts[d])));
}
}
Also, looking at http://lucene.apache.org/java/docs/fileformats.html I don't
even see any mention of .sN files.
Does anyone has an explanation for this before I start digging?
Thanks,
Otis
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