How marklogic compute weight to calculate score for a document

Question

I am exploring relevance info to get information about the factor which influence scoring in Marklogic.

<qry:relevance-info xmlns:qry="http://marklogic.com/cts/query">
  <qry:score
    formula="(256*scoreSum/weightSum)+(256*qualityWeight*documentQuality)"
    computation="(256*1274/4)+(256*1*0)">81536</qry:score>
..
</qry:relevance>

Does anyone have idea about weightSum factor?

What are the things Marklogic consider to compute the value for weightSum.

Answer 1

Using Weights to Influence Scores

Use a weight in a query sub-expression to either boost or lower the sub-expression contribution to the relevance score.

For example, you can specify weights for leaf-level cts:query constructors, such as cts:word-query and cts:element-value-query; for details, see XQuery and XSLT Reference Guide. You can also specify weights in the equivalent Search API abstractions, such as the structured query constructs value-query and word-constraint-query, or when defining a word or value constraint in query options.

The default weight is 1.0. Use the following guidelines for choosing custom weights:

• To boost the score contribution, set the weight higher than 1.0.
• To lower the score contribution, set the weight between 0 and 1.0.
• To contribute nothing to the score, set the weight to 0.
• To make the score contribution negative, set the weight to a negative number.

Scores are normalized, so a weight is not an absolute multiplier on the score. Instead, weights indicate how much terms from a given query sub-expression are weighted in comparison to other sub-expressions in the same expression. A weight of 2.0 doubles the contribution to the score for terms that match that query. Similarly, a weight of 0.5 halves the contribution to the score for terms that match that query. In some cases, the score reaches a maximum, so a weight of 2.0 and a weight of 20,000 can yield the same contribution to the score.

Adding weights is particularly useful if you have several components in a query expression, and you want matches for some parts of the expression to be weighted more heavily than other parts. For an example of this, see Increase the Score for some Terms, Decrease for Others.