What identification scheme should I use?

Question:

What identification scheme should I use, Shopify global format, product ID or SKU?

Answer:

Item identification matters. This is a very important question as once chosen, item identification will need to be aligned across Google products (Google Shopping, Google Ads, conversion tracking, product feeds, etc.). Also, all sales data is stored with the item ID, so a stable identification scheme should be preferred. Google Shopping treat each variant as a separate item, so identification scheme should take that into account.

Following is the list of identification scheme, from most favorable first:

• SKU (variant SKU, not product SKU). This could be future proof as well, as generally SKU does not depend on the ecommerce platform. If you migrate from Magento to Shopify, you can keep the items SKU the same after migration and effectively retain all the sale performance history in Google Ads.
• Variant ID. This is the default choice of the Facebook channel. A downside of this scheme is that it depends on Shopify variant ID so if you migrate your product to another Shopify store, or out of Shopify, sale data is lost.
• Product ID_Variant ID. Same as Variant ID. This is used by default by Symprosis app, which provide no more benefits than the Variant ID option, while taking more space. A (not very significant) benefit is that you can look up the item in Google Shopping by product ID.
• Shopify_XX_Product ID_Variant ID (or Shopify global format). XX is the 2-letter country code (GB, US, etc.). This is the choice of the Shopify Google & Youtube channel. However, this provides no more benefit than the Product ID, while leaving the item ID taking up more space. This also create confusion when merchant needs to target more than one markets that the items need to be duplicated, while they do not need to, and should not be duplicated. Item only needs to be “duplicated” when they contain different content (e.g. product description in different languages or price in different currencies). Even then, they can, and should, use the same identification, as we then can relate localized versions of the same product across Google products (Google Merchant Center, Google Ads, etc.).