3. The method of claim 2 , wherein the constructing a histogram includes: counting each value in a document; outputting a collection of value-count pairs sorted by said counting; and partitioning the collection of sorted value-count pairs into said buckets.
3. The method of claim 2 , wherein the constructing a histogram includes: counting each value in a document; outputting a collection of value-count pairs sorted by said counting; and partitioning the collection of sorted value-count pairs into said buckets. 4. The method of claim 3 , wherein the synopsis of each bucket includes data reflecting occurrence counts of q-grams of the values that are associated with the bucket.