As for right now there is no real way to do this (this is not a “normal” database). I think there might be some workarounds that the community came up with, but I do not remember for sure.
What I’ve come to do is keep a separate collection of all the IDs I’ve upserted in each Pinecone Index so I can easily fetch all of them. The problem here is if you are using other clients (Langchain for example) that keep the upserting ids “hidden” from you by default.