The Force.com Multitenant Architecture: Understanding the Design of Salesforce.com’s Internet Application Development Platform

The UniqueFields Pivot Table

Force.com lets an organization indicate when a field in an object must contain unique values (case-sensitive or case-insensitive). Considering the arrangement of the Data table and shared usage of the Value columns for custom field data, it is not practical to create unique database indexes for the table (similar to the problem discussed in the previous section for non-unique indexes).

To support uniqueness for custom fields, Force.com uses the pivot table called UniqueFields; this table is very similar to the Indexes pivot table except that the UniqueFields table’s underlying database indexes enforce uniqueness. When an application attempts to insert a duplicate value into a field that requires uniqueness, or an ...