pgbouncer information (#1471)

Author: tmasternak

README.md

@@ -42,3 +42,7 @@ All tests use the default connection string `Data Source=.\SQLEXPRESS;Initial Ca
   - `receiver` owner `db_owner`
   - `sender` owner `db_owner`
   - `db@` owner `db_owner`
+
+## Connection pooling for PostgreSQL
+
+Deployments with multiple endpoints running on PostgreSQL require external connection pooling e.g. [using pgBouncer](/docs/postgre-with-pgbouncer.md)

doc/postgre-with-pgbouncer.md

@@ -0,0 +1,51 @@
+## Postgre Sql transport with pgBounder
+
+## Connection string changes
+
+Running with external connection pool like pgBounder requries changes to the connection string as described in [NpgSQL compatibility guide](https://www.npgsql.org/doc/compatibility.html#pgbouncer).
+
+## Sample deployment
+
+```docker-compose
+version: '3.8'
+services:
+  db:
+    image: postgres
+    container_name: local_pgdb
+    restart: always
+    command: -c 'max_connections=100'
+    environment:
+      POSTGRES_USER: user
+      POSTGRES_PASSWORD: admin
+    volumes:
+      - local_pgdata:/var/lib/postgresql/data
+
+  pgbouncer:
+    image: edoburu/pgbouncer:latest
+    environment:
+      - DB_HOST=local_pgdb
+      - DB_PORT=5432
+      - DB_USER=user
+      - DB_PASSWORD=admin
+      - ADMIN_USERS=postgres,admin
+      - AUTH_TYPE=scram-sha-256
+      - MAX_CLIENT_CONN=70
+    ports:
+      - "5432:5432"
+
+  pgadmin:
+    image: dpage/pgadmin4
+    container_name: pgadmin4_container
+    restart: always
+    ports:
+      - "5050:80"
+    environment:
+      PGADMIN_DEFAULT_EMAIL: [email protected]
+      PGADMIN_DEFAULT_PASSWORD: admin
+    volumes:
+      - pgadmin-data:/var/lib/pgadmin
+
+volumes:
+  local_pgdata:
+  pgadmin-data:
+```