Sorry to contradict, Erik, but the Highlighter's QueryScorer will make
use of IDF, given a reader, in order to better prioritise which are the
"best" bits of a document.
However, In the particular example given, the criteria includes several
non-text fields which are not useful for IDF and general scoring
purposes - these are perhaps better expressed using a filter of some
form. Otherwise, why should the scarcity of a particular date in the
given range boost one matching document above others? These numeric-type
fields are simply mandatory boolean "hygiene factors" and should
ideally play no part in highlight selection or results ordering in
general based on their IDF or TF.
Cheers,
Mark
Erik Hatcher wrote:
Harini,
I'm not sure I understand what you're asking. IDF doesn't factor
into highlighting.
IDF calculations are useful in scoring documents during a search,
such that the most relevant documents are returned, but again this is
unrelated to highlighting.
Could you elaborate on what you're after?
Erik
On Dec 30, 2005, at 12:02 PM, Harini Raghavan wrote:
Hi,
I have a requirement to highlight search keywords in the results and
display the matching fragment of the text with the results. I am using
the Hits highlighting mentioned in Lucene in Action.
Here is the search query(BooleanQuery) I am passing to the
IndexSearcher
and QueryScorer:
+DocumentType:news
+(CompanyId:10 CompanyId:20 CompanyId:30 CompanyId:40)
+FilingDate:[20041201 TO 20051201]
+(Content:"cost saving" Content:"cost savings" Content:outsource
Content:outsources Content:downsize Content:downsizes
Content:restructuring Content:restructure)
I do not quite understand how the query scoring actually works & how
Inverse Document Frequency(IDF) calculations are useful? Can
someone shed some light on this using the given query as an example?
Thanks,
Harini
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