Store user id as UUID in PostgreSQL #2
Description
Since we use Keycloak as our user authentication service, we are pushed into using UUIDs as user ids. These are rather long and therefore not as performant as simple integers, which itself may have to change in order to increase the performance of the matchengine.
But this issue is about a performance-bug that should be fixed even with using UUIDs: We store the UUIDs as VARCHAR(36) in the PostgreSQL database, which is bad practice, and should be fixed.
To achieve this, the DB user_id fields should be set to be of type UUID rather than VARCHAR(36); check out the scripts in the migrations-folder for this.
Then, it would probably make sense to use a UUID-datatype in Rust too, in the file src/storage/models.rs, and get the application and the DB to understand each others datatype.