sumDocFreq

The total number of posting list entries for this field, in the range [.docCount .. .sumTotalTermFreq]. This is the sum of term-document pairs: the sum of TermStatistics.docFreq across all terms. It is also the sum of each document's unique term count for this field across all documents.

This value is always a positive number, always at least .docCount, and never exceeds .sumTotalTermFreq. @see Terms#getSumDocFreq()