Class JoinUtil

Method for query time joining.

Execute the returned query with a to retrieve all documents that have the same terms in the to field that match with documents matching the specified fromQuery and have the same terms in the from field.

In the case a single document relates to more than one document the multipleValuesPerDocument option should be set to true. When the multipleValuesPerDocument is set to true only the the score from the first encountered join value originating from the 'from' side is mapped into the 'to' side. Even in the case when a second join value related to a specific document yields a higher score. Obviously this doesn't apply in the case that None is used, since no scores are computed at all.

Memory considerations: During joining all unique join values are kept in memory. On top of that when the scoreMode isn't set to None a float value per unique join value is kept in memory for computing scores. When scoreMode is set to Avg also an additional integer value is kept in memory per unique join value.