Introducing hit Count as an alternative to score
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Key: SOLR-2953
URL: https://issues.apache.org/jira/browse/SOLR-2953
Project: Solr
Issue Type: New Feature
Components: search
Affects Versions: 4.0
Reporter: Kaleem Ahmed
Fix For: 4.0
As of now we have score as relevancy factor for a query against a document, and
this score is relative to the number of documents in the index. In the same way
why not have some other relevancy feature say "hitCounts" which is absolute for
a given doc and a given query, It shouldn't depend on the number of documents
in the index. This will help a lot for the frequently changing indexes , where
the search rules are predefined along the relevancy factor for a document to be
qualified for that query(search rule).
Ex: consider a use case where a list of queries are formed with a threshold
number for each query and these are searched on a frequently updated index to
get the documents that score above the threshold i.e. when a document's
relevancy factor crosses the threshold for a query the document is said to be
qualified for that query.
For the above use case to satisfy the score shouldn't change every time the
index gets updated with new documents. So we introduce new feature called
"hitCount" which represents the relevancy of a document against a query and it
is absolute(won't change with index size).
This hitCount is a positive integer and is calculated as follows
Ex: Document with text "the quick fox jumped over the lazy dog, while the lazy
dog was too lazy to care"
1. for the query "lazy AND dog" the hitCount will be == (no of occurrences of
"lazy" in the document) + (no of occurrences of "dog" in the document) =>
3+2 => 5
2. for the phrase query \"lazy dog\" the hitCount will be == (no of
occurrences of exact phrase "lazy dog" in the document) => 2
This will be very useful as an alternative scoring mechanism.
I already implemented this whole thing in the Solr source code(that I
downloaded) and we are using it. So far it's going good.
It would be really great if this feature is added to trunk (original Solr) so
that we don't have to implement the changes every time a new version is
released and also others could be benefited with this.
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