List Import Marketo - do not want to overwrite existing fields

[stacenic]

Quick question - I am sure many of you have imported lead lists into Marketo (that are then synced over to salesforce). When importing a list of leads - I want to be sure if the record already exists in our Marketo instance - that some of the existing values are not overwritten - ie if Lead Source and Lead Source details already exist - they cannot be overwritten. I know under ADMIN in Marketo, when clicking to field management - I can block updates under certain scenarios but I don't see an option to block an update if the value already exists. I'm a previous HubSpot superuser - so I know in HubSpot you can adjust the sync between HubSpot and SFDC to not overwrite existing values (that you want to remain the same such as lead source) - and have one system be the system of truth - ie if the value exists in one system but not the other then use the one system's value. If anyone has had this experience please let me know how you resolved the issue - thank you! 

[SanfordWhiteman · Accepted solution]

Block field updates does mean if the value already exists in Marketo-speak.

The first time a field is set isn't considered an update.

[stacenic]

Thank you for responding! So if I update the field to say block when uploading a list - as long as the record already exists in Marketo, and the corresponding field already has a value, then there will be no updates. But if the field is blank then an update will be made? 

[Beth_Massura · Accepted solution]

That's correct! You can write to the field once and then it will block further updates.

[SanfordWhiteman]

Yes, I just wouldn't use the word "update" for the first time it goes from empty to non-empty.