Abstract: A method of querying a data structure having a plurality of records and data items is disclosed. Each record has an index identifying the record and a collection of paths pointing to a selection of data items. Each path corresponds to a data variable. The method includes receiving a query to sort the records according to a data variable. Creating a first array and defining start points for data items are performed. Storing the index of the record after the start point and determining an end point for each start point are performed. Determining locations in each sequence of locations and returning the locations to designate where the record indexes may be found are performed.

Abstract: A method of sorting a database of records and data items, in which each record has an identifier, data variables and paths pointing to data items being the value of the data variables is disclosed. The database has a first and second frequency for each path of the first and second data variables, respectively. The method includes creating an intermediate array having a section for each value of the second data variable. Storing the identifier of each record. Creating a final array having sections for each value of the first data variable. Storing the identifier of the records into the section of the final array corresponding to the value of its first data variable. Identifying break points in the final array. Repeating the previous two steps for each section of the intermediate array. Creating a break point index.