A SumIndexField is a decimal field that can be attached to a key definition. This is the fundamental feature of the Microsoft Dynamics NAV database that forms the basis for FlowFields. SumIndexFields permit fast calculation of sums of numeric columns in tables, even in tables with thousands of records. This occurs because SumIndexFields are maintained when the database record is updated.
Advantages of SumIndexFields
SumIndexFields enable the speedy calculation of sums of columns. The resulting totals are displayed in FlowFields.
For example, assume you want the sum of all the values in the Amount field. In a conventional database system, the DBMS is forced to access every record and add each value in the Amount field. This is a time-consuming operation in a database with thousands of records. With Microsoft Dynamics NAV, it can take as little as two accesses (if the best key is used) to sum the Amount for these records.
This special index structure, a SumIndexField, is associated with a key. Each key can have up to 20 SumIndexFields.
During database design, a decimal field can be associated with a key as a SumIndexField. This tells the DBMS to create and maintain a structure that contains the accumulated sum of values in a column. When a new current key is selected, any SumIndexFields associated with it become accessible.