Delving into field norms
A norm is part of the calculation of a score that's used to measure relevancy. When we search, a score is calculated for each matching result. This score will then be used to sort the end results. The score is what we refer to as a relevancy score.
Norms are calculated per indexed Field. This is a product of index time calculation (based on TFIDFSimilarity) and lengthNorm (a calculated factor that favors a shorter document). The higher value can help boost the relevancy of a document, which means that the document will rank higher in search results.
To further influence the search results relevancy, Lucene allows for two types of boosting: index time boost and query time boost. Index time boost is set per indexed field. ...
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