Methods and systems for storing web-site visitor data in a specific bucket among a plurality of buckets based on a unique visitor identifier. The methods and systems may dynamically change the number of buckets based on certain conditions, such as when one of the buckets reaches a predetermined size. Several processors may be used in parallel to process the visitor data from two or more of the buckets simultaneously, for example to generate or obtain report data. The systems and methods may aggregate the report data into a result table.