public PredicateIndexStats getStats() {
        return new PredicateIndexStats(zeroConstraintDocuments, intervalIndexBuilder,
                boundsIndexBuilder, intervalStoreBuilder, conjunctionIndexBuilder, nZStarDocuments, nZStarIntervals);
    }
Retrieves metrics about the current index.

@return an object containing metrics
predicate-search/src/main/java/com/yahoo/search/predicate/PredicateIndexBuilder.java