Number of projections

Hi all,

Been playing around the event store and I have to say I’m very impressed. Great work!

I’m not sure if I’m doing this right though, so would appreciate some guidance.

If let’s say I have a website and users can do random things on the website. I would like to set up some projections such as

/projections/eventType1 (these are the various events that occur as the user uses the website)



and then also

/projections/user_1 (this stream is the list of events that a specific user has done)



If I have 1,000,000 users … I will have 1,000,000+ projections. Just wondering if this is the correct way to approach it.

Feedback / guidance much appreciated.



Millions are expected and pretty common :slight_smile:

You will note though that when you use linkto it does not in single node copy the data of the event but is just a link

Consider 5m streams with 2 events each (1000 bytes) we are only at about 2gb :slight_smile:

The projection is pretty easy (just emit a linkto the stream named user)



btw: We test regularly with hundreds of millions so don't worry too much :slight_smile:

That said if you get to the hundreds of millions let us know as we
will bump priority on the 64 bit hashed index (interchangable with
32bit one but will give less collisions while using a bit more space
for scenarios like this.

Thanks for the reply Greg!

Much appreciated, and looking forward to seeing what nice things I can do with the eventstore … :slight_smile: