SQL Performance is a very big topic. So many ways how to achieve what you need. Just indexes not enough, you need right indexes and right queries. I think it will be much more productive if you provide some examples of your classes with populate, and queries. So, anybody will be able to reproduce your issue and offer some ways how to solve it.

When you have || in Id, it usually means, that you have additional Index by two or more fields, and marked as IdKey. Something like this.

Property RollNo As %String;

Property Marks As %String;

Index RollNoMarks On (RollNo, Marks) [ IdKey, Unique ];

Here we have some two properties, to store both values separately, but we used both of their values as IdKey.

Now it is possible to check of existing an object by ##class(User.School).%ExistsId(RollNo_"||"_Marks), or open id by  ##class(User.School).%OpenId(RollNo_"||"_Marks)

But in additional to this system methods, we now have some new ones which construct with index name and "Exists", "Open" and so on. But call will be a bit different. You should pass all values separately in this way.

##class(User.School).RollNoMarksExists(RollNo, Marks)

##class(User.School).RollNoMarksOpen(RollNo, Marks, , .sc)

You can try any of these ways, and you should remember about Status variable, which may help you to understand what's happening.

do $system.OBJ.DisplayError(sc)

will decode status

It's actually a very interesting question, and actually mostly depends on what you really want to achieve.

First of all, you can redefine Dockerfile name in docker-compose.yml

version: '3.7'
services:
  myapp:
    build:
      context: .
      dockerfile: Dockerfile.test

or just in docker build

docker build -f Dockerfile.test .

But there is another use case when you would need even different docker-compose.yml files. If you would want to split running like in the production and development environment.

You can just do it this way, 

docker-compose up --build -f docker-compose.prod.yml

docker-compose up --build -f docker-compose.dev.yml

But I would recommend a bit different way, based on the possibility to extend one YAML file with the content of another.

So we need main docker-compose.yml

version: '3.7'
services:
  iris: 
    extends:
      file: docker-compose.${MODE:-dev}.yml
      service: iris
    ports:
      - '${WEBPORT:-52773}:52773'

which in fact declares just common settings, which will be the same for dev and prod.

Then look at docker-compose.dev.yml, for example I'm using IRIS community edition for development

version: '3.7'
services:
  iris: 
    image: store/intersystems/iris:2019.3.0.302.0-community
    volumes:
      - ./src:/opt/myapp/src

and docker-compose.prod.yml, and licensed version for testing production environment

version: '3.7'
services:
  iris: 
    image: store/intersystems/iris:2019.3.0.302.0
    volumes:
      - ~/iris.key:/usr/irissys/mgr/iris.key

By default when you will start docker-compose environment, it will use dev. Because here ${MODE:-dev} it uses environment variable MODE with default value as dev. Then, you can change it this way.

MODE=prod docker-compose up --build

But you can also create file .env with values for any environment variables which you would like to redefine. So, in our case it can be like this, with changed WEBPORT as well.

MODE=prod
WEBPORT=52774

It is not a big problem to make it with Caché. But I would recommend you to look at different ways. Using Caché just as a reverse proxy, looks like a sledgehammer to crack a nut.

First of all, you should go from an original source of users, I don't see it in your question, but it can be LDAP/AD or something else outside of Caché. 

I would look at Nginx for example, which is actually very flexible.

Have you looked at @Daniel Kutac series of articles about OAuth2? In part 3 he mentioned about debugging. Kind of like this should help you.

set ^%ISCLOG=5
set ^%ISCLOG("Category","OAuth2")=5
set ^%ISCLOG("Category","OAuth2Server")=5