Selecting multiple event streams for query (and projections) based on stream name prefix

EventStoreDB
1

Hello, fellow EventStorers!

We are storing each aggregate’s events in its own stream. For example, we have streams named user_0001, user_0002, user_0003 and so forth.

I would like to build a query in the Admin UI to process events for all the streams whose names start with (thus those that have a prefix of) “user_”.

According to the documentation, it is possible to select multiple streams by using the fromStreams() method. Using this method, I can successfully build a query (and projections) by using a selector like fromStreams(['user_0001', 'user_0002', 'user_0003']).

But naturally, we cannot know all possible stream names up-front.

What is the best approach to use to select all streams with a prefix of “user_” for an Admin UI query (or for a projection)?

Apologies if this is not the best category in which to post my question.

2

Hi,
if you use a stream name pattern of ‘[type]-[id]’ (note: hyphen rather than underscore) and turn on the standard projections event store will do this for you by creating link to streams of the format ‘$ce-[type]’
so the ‘$ce-user’ stream would have all events in order from all three user streams in your example.
-Chris

3

Thank you @chris.condron

For those seeking additional information, here is a link to the section of the documentation that deals with these and related system projections: https://developers.eventstore.com/server/v20/server/projections/system-projections.html#enabling-system-projections