What is the purpose of the coalesce field when importing data?

If a match is found using a coalesce field, the existing record is updated, not a new record inserted.

The purpose of a coalesce field (or a combination of fields) in data imports is to serve as a unique key to identify if an incoming row from the import set matches an existing record in the target table. This identification dictates whether the import process should update the existing record or insert a new one.

If a match is not found based on the coalesce field, a new record is inserted into the target table, rather than updating an existing one.

While coalescing helps prevent duplicates, its primary purpose is record identification for update/insert logic, not a general 'merge duplicate records' function, which often implies a separate de-duplication process.