Variant Extracts

Both standard and working extracts can be variant extracts. Variants are a special type of extracts in which elements are not claimed from the parent. They are designed to allow users to try out different designs, which then may or may not be written back to the primary.

When variants are used, all changes are merged together on issue. Changes are handled at attribute level, so that different users can change different attributes on the same element and then merge their changes. No locking is applied to a variant extract, and any locks applied to other extracts are ignored. This allows many users to modify the same element in a given session, but has the disadvantage that any conflicts will not be found until the changes are issued. If two users modify the same attribute, the last change to be merged takes precedence.

The AVEVA base product will make sure that all merges comply with the basic database rules, that is, the data will comply with all Database Integrity Checker (DICE) checking requirements, but it cannot check that the data makes sense in the AVEVA base product design terms. It is recommended, therefore, that data consistency and clash checks are carried out on the resulting merged data.