Issue with Salesforce Adapter


Anyone help me to resolve the below issue with Salesforce Adapter?

Issue: I am doing an upsert operation to Salesforce object which contains 100 fields. Out of 100 fields at run time we may not get 5 or 6 fields.

When we try to do upsert second time without passing any values to few fields at run time (even though we selected in adapter service), it wiping the existing values for those fields for which we are not passing any values.

We can’t check for each field value whether exists or not as some times we have 200+ fields as well.