Is there a difference in performance between case A: one collection of 1M documents, case B: 50 collections of 20-30K documents each?

Latter should be much faster with higher memory overhead because the word/token index is not shared. But for the scale of 1M should not make too much of a difference. A good middle ground will be to use 100 collections where you can "shard" by

user_id % 100

to map to the collection name.

By "higher memory overhead" you mean it will end up consuming more RAM?

Correct.

Would it be roughly 2x or more?

Hard do say. May not be that much I think. Very difficult to answer it because it depends on for e.g. how frequently words appear in the dataset and their distribution.

I'm not sure what you mean by "shard to map to the collection name", is there anything on the docs regarding this?

Are you going to have separate sets of users or customers?

I understand, thanks!

Assume that you have 100,000 customers. But you want to fit them into 100 collections which is a middle ground between creating 1 collection per customer and having just 1 collection for all customers. So we will have

collection_0

collection_1

, etc. To find this ID, we can calculate that by doing

user_id % 100

-- this produces a number between 0 to 99 that maps to 100 different collections.

ah I see, but doesn't that mess with "scope"? user1 shouldn't be able to access user2 docs

That will be the same issue when using a single collection right.

Aren't scoped keys for limiting search at the collection level?

No you can embed filters into them. We have elaborated on that here: https://typesense.org/docs/0.21.0/api/api-keys.html#generate-scoped-search-key

Oh, in that case why not use one collection for all users (with scoped key and filters)? I was going to use one collection for each user and scoped keys as "ACL"

If you use one collection per user, you don't need scoped API key. You can generate normal API key per collection. Scoped API keys are meant to be used for embedding filters that are baked into the key itself so you can host multiple users within the same collection.

I see

Both scoped API key and regular API key are secure. Once a scoped API key is created with an embedded user_id: X filter it is as secure as using 1 collection per user_id. However on paper, 1 collection per customer gives clear separation of data.

thanks!