This example shows an upsert UPDATE request that does not specify the primary index in its WHERE clause.
UPDATE sales SET item_count = item_count + 1 WHERE sale_date = '05/30/2000' ELSE INSERT INTO sales (10, '05/30/2000', 1);
When the primary index is not specified in the UPDATE portion of an upsert request, the operation could have to perform an all-row scan to find rows to update. This is not the purpose of upsert form of UPDATE. This case returns an error.