When query performance is of utmost importance, aggregate join indexes offer an extremely efficient, cost-effective method of resolving queries that frequently specify the same aggregate operations on the same column or columns. When aggregate join indexes are available, the system does not have to repeat aggregate calculations for every query.
You can define an aggregate join index on two or more tables, or on a single table. A single-table aggregate join index includes a summary table with:
- A subset of columns from a base table
- Additional columns for the aggregate summaries of the base table columns