The Similarity.lengthNorm() is a callback from Lucene that gives you
the information you seek. Of course, the trick still is how to use
that. Perhaps you can describe a bit more about why you need that
length.
On Sep 4, 2009, at 11:34 AM, mike.schultz wrote:
For various statistics I collect from an index it's important for me
to know
the length (measured in tokens) of a document field. I can get that
information to some degree from the "norms" for the field but a) the
resolution isn't that great, and b) more importantly, if boosts are
used
it's almost impossible to get lengths from this.
Here's two ideas I was thinking about that maybe some can comment on.
1) Use copyto to copy the field in question, fieldA to an addition
field,
fieldALength, which has an extra filter that just counts the tokens
and only
outputs a token representing the length of the field. This has the
disadvantage of retokenizing basically the whole document (because
the field
in question is basically the body). Plus I would think littering
the term
space with these tokens might be bad for performance, I'm not sure.
2) Add a filter to the field in question which again counts the
tokens.
This filter allows the regular tokens to be indexed as usual but
somehow
manages to get the token-count into a stored field of the document.
This
has the advantage of not having to retokenize the field and instead of
littering the token space, the count becomes docdata for each doc.
Can this
be done? Maybe using threadLocal to temporarily store the count?
Thanks.
--
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--------------------------
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