We consider the "view data lineage" problem in a warehousing environment:
For a given data item in a materialized warehouse view, we want to identify
the set of source data items that produced the view item. We formally define
the lineage problem and develop lineage tracing algorithms for relational 
views with aggregation. Our algorithms are efficient and provide consistent
lineage tracing in a multi-source data warehousing environment. Using our
results, we can build a tool that allows analysts to browse warehouse data,
select view tuples of interest, then "drill-down" to examine the source data
that produced them.