Techniques for online exploration of large object-relational datasets

We review techniques for exploring large object-relational scientific and statistical databases in an interactive online manner. The idea is to provide continuously updated running estimates of the final query results to the user, along with an indication of the precision of the estimates. The user can then halt the query as soon as the answer is sufficiently precise - the time required to obtain an acceptable approximate answer can be faster by orders of magnitude than the time needed to completely process the query. We describe methods for online processing of aggregation queries, online visualization, and online display of a set of result records. We also describe methods that use precomputed results to rapidly obtain approximate query answers.