24. The database system of claim 19 , where further query optimization includes: determining one or more plans for executing the query.
24. The database system of claim 19 , where further query optimization includes: determining one or more plans for executing the query. 25. The database system of claim 24 , where one of the one or more plans includes: scanning a table to locate rows that satisfy one or more conditions; and summing one or more columns in the rows that satisfy the one or more conditions.