QueryService - Correct pagination with a single query that loads unknown number of records.

With advanced queries, part of QueryServices, a general problem exists with a single query that loads an unknown number of records and correct pagination of this result set. For example, if retrieving information about process instance/task with variables multiple results for each individual process instance may be returned. However, the desired pagination is across unique instance id's, not the actual number of rows returned by this single query. To achieve proper pagination one must apply multiple queries.

The desired enhancement is to support proper pagination in these cases with a single advanced query.