Lucene/Solr打分机制的分析（二）

Solr scoring based on tf-idf scoring model. Refer to https://wiki.apache.org/solr/SolrRelevancyFAQ.
tf stands for term frequency - the more times a search term appears in a document, the higher the score

idf stands for inverse document frequency - matches on rarer terms count more than matches on common terms

coord is the coordination factor - if there are multiple terms in a query, the more terms that match, the higher the score

lengthNorm - matches on a smaller field score higher than matches on a larger field

index-time boost - if a boost was specified for a document at index time, scores for searches that match that document will be boosted.

query clause boost - a user may explicitly boost the contribution of one part of a query over another.

Document-boost vs Field-boost

Index-time boost vs query-time boost

How can I boost the score of newer documents

- Do an explicit sort by date (relevancy scores are ignored)

- Use an index-time boost that is larger for newer documents

- Use a FunctionQuery to influence the score based on a date field.