Product Sync will try to match existing content items in your Content Library against the content items declared in your Google product feed file by comparing their URLs. Content items in your content library with the same URL will be replaced with content from the Google Product Feed. Any content items created by Google Product Sync will be synchronized automatically, as long as the content remains in your Google product feed.

	Present in your Content Library	Present in Google Product Feed	Will be managed by Product Sync
Red Shirt	Yes	Yes	Yes
Yellow Sneakers	Yes	No	No
Leather Jacket	No	Yes	Yes
Pink Heels	No	No	No

Expired Content

Product Sync will automatically expire content (by setting its expire_date field), when it detects it is no longer present in the feed file. Expired content will still be accessible in your content library, and remain there until you permanently delete via the API. To restore expired content, simply add it back in to your feed file.

Content Spider

Updates to your existing content are either done through Sailthru's content API or using the content spider. Once you start using Product Sync, the content or Javascript spider will stop operating on items that are handled by Product Sync. Considering the example mentioned above, the spider will continue to work on products "Yellow Sneakers" and "Pink Heels" as those items are not managed by Product Sync. 

Content API

We don't recommend that you use the content API to update content managed by Google Product Sync as it may cause some data inconsistencies. You can update your existing content as long as it is not included in your Google product feed file.  For example, if you wanted to update the price of a product from $10 to $20, you might submit an API request to update the price. However, if the price for that product is still $10 in the Google product feed, then Product Sync may overwrite your API change and set the price back to $10.

Tags

Content tags power our recommendation algorithms, so it's important to handle them correctly. When Product Sync updates existing content, it will append its generated tags to any existing tags. This means you won't lose any tags on your existing content when you start using Product Sync. Here are some examples of how existing tags will be combined with tags generated by Product Sync:

Products	Tags on existing content	Tags generated by Product Sync	Combined tags
Red Shirt	red, shirt	clothing	clothing, red, shirt
Yellow Sneakers		yellow, shoes	yellow, shoes