9. The data processing system as claimed in claim 7 , wherein the summary filter transformation system is configured to analyze the filter condition to determine the filter group by: identifying aggregates of the filter condition; for each identified aggregate, identifying an aggregate group of the aggregate, the aggregate group comprising a list of expressions over which the aggregate is computed; and selecting the aggregate group with the lowest level of granularity as the filter group.
9. The data processing system as claimed in claim 7 , wherein the summary filter transformation system is configured to analyze the filter condition to determine the filter group by: identifying aggregates of the filter condition; for each identified aggregate, identifying an aggregate group of the aggregate, the aggregate group comprising a list of expressions over which the aggregate is computed; and selecting the aggregate group with the lowest level of granularity as the filter group. 11. The data processing system as claimed in claim 9 , wherein the standard aggregates comprise at least one of: MIN; MAX; SUM; AVG; COUNT; or COUNT(*).