1. What is a supplemental feed?

A supplemental feed is a method of adding new or missing data from the primary feed into your marketing campaigns. This type of feed only serves the purpose of filling in the required or optional data to the primary source, not entirely replacing it. 

Marketers can use supplemental feeds to optimize their shopping campaigns. Additional data can be added, both new and revised, to diversify your ad listings. 

2. Differentiate between Primary and Supplemental Feed

2.1. Primary Feed 

A primary feed is the one that stores all of your system’s data, and usually the feed that you use to upload on Google Merchant Center. You can perform almost every possible action on a primary feed, namely modifying data on your feed, customize geo targeting settings and implement rules for optimization.

2.2. Supplemental Feed

A supplemental feed is a secondary feed that works as an extra tool to alternate data. You cannot directly upload it to Google Merchant Center as the main feed. Instead, it is used to support the primary feed in terms of product management. Supplemental feeds are used to change, add or overwrite information on the primary feed, troubleshoot Google Merchant Center errors, etc.

2.3. When to add supplemental feeds

• Your feeds lacks information:

It is obvious that when your primary feed lacks the necessary information, you should use supplemental feeds to complete the data. For example, if you want to begin selling custom label products, you have to use a supplemental feed to add in the new product type.

• You want to replace an attribute:

With supplemental feeds, you can easily override the existing data with a new one. The most common use for this purpose is when a keyword in the titles needs to be changed. After you have uploaded a new product listing to your supplemental feed, you will put it on Google Merchant Center to process and change the names of old ones.