How to identify goods when uploading to VK?

Question

In contact with

Hello.
I am preparing the functionality for unloading goods on VK. The API as a whole is not complicated, making the first full upload easy.
And how to compare goods during repeated unloadings so that they do not multiply from each unloading? They don’t even have any field in the API where you could specify some kind of product identifier.

Answer 1

Most likely, this needs to be decided at the application level. Didn't think about not adding a product, but completely updating it?

Answer 2

So I ask for this, after all, that out of 10 uploads, the first one should be the addition of goods, the remaining 9 should be an update.
If it’s not entirely clear, then I’ll clarify that there are 10 products in VK, and we have 10 products. We take one and want to upgrade. How to know which product to upgrade it to. We do not consider the search option by name.