How do we use CQRS with @nestjs/cqrs to solve scalability issues in high-traffic apps?

import { Module } from '@nestjs/common';
import { CqrsModule } from '@nestjs/cqrs';
@Module({
  imports: [CqrsModule.forRoot()],
  // your controllers, handlers...
})
export class AppModule {}
      

export class CreateUserCommand {
  constructor(
    public readonly name: string,
    public readonly email: string,
  ) {}
}
      

import { ICommandHandler, CommandHandler } from '@nestjs/cqrs';
@CommandHandler(CreateUserCommand)
export class CreateUserHandler implements ICommandHandler<CreateUserCommand> {
  async execute(command: CreateUserCommand) {
    // Write to main DB/transactional store
    const user = await this.userRepo.create(command);
    return user.id; // Return result
  }
}
      

 export class GetUserQuery {
  constructor(public readonly id: string) {}
}
      

import { IQueryHandler, QueryHandler } from '@nestjs/cqrs';
@QueryHandler(GetUserQuery)
export class GetUserHandler implements IQueryHandler<GetUserQuery> {
  async execute(query: GetUserQuery) {
    // Read from cache/read replica
    return this.userReadService.findById(query.id);
  }
}
      

import { CommandBus, QueryBus } from '@nestjs/cqrs';

@Controller('users')
export class UserController {
  constructor(
    private commandBus: CommandBus,
    private queryBus: QueryBus,
  ) {}

  @Post()
  async create(@Body() dto: CreateUserDto) {
    return this.commandBus.execute(new CreateUserCommand(dto.name, dto.email));
  }

  @Get(':id')
  async find(@Param('id') id: string) {
    return this.queryBus.execute(new GetUserQuery(id));
  }
}