Firebolt's aggregating index pre-calculates and stores aggregate function results for improved query performance, similar to a materialized view that works with Firebolt's F3 storage format. Firebolt selects the best aggregating indexes to optimize queries at runtime, avoiding full table scans. These indexes are automatically updated with new or modified data to remain consistent with the underlying table data. In multi-node engines, Firebolt shards aggregating indexes across nodes, similar to the sharding of the underlying tables.