If an SQL (any) database is fast there are a few possibilities: 1. There is an index 2. The database is in memory and a scan is running in process 3.

If an SQL (any) database is fast there are a few possibilities: 1. There is an index 2. The database is in memory and a scan is running in process 3. The query result was precomputed 4. The query was not that hard With couchdb you could create a view on sku and week, and reduce to a count.