Actual numbers are not important at the moment - "high" depends on many factors and could be a result of a traffic spike.
Caches will be put in place - of course, but since the infrastructure will be designed with many nodes and the "reader" nodes will be within an autoscaling configuration i would like to take advantage of that - there are certain things that i wont be able to cache so calls to the database will be necessary.
Here is a very basic example on the situation with an say e-commerce site:
- in the backend i open an order to view/edit - i should also get "connected/similar" orders - which in some cases be several hundred. Also get some external details for that orders, some warehouse information about stocks and packages for each one.
- now imagine there are 150 people doing the same thing on a database with several million records in the order tables alone while the frontend traffic continues - several thousand people all doing all sort of crap - making new orders, updating old ones, tracking packages and stuff.
- i would like to be able to direct all those read-only queries to the "reader" nodes as they need to be accurate.
Assuming the question is not on cache, query optimisations and weather or not i would have user logins, whats the best way to achieve this?
Can i switch model database on-the-fly by only changing $DBgroup?
Is if in my controllers constructor i instantiate a model like that:
PHP Code:
<?php namespace App\Controllers;
use App\Models\OrdersModel;
class Test extends BaseController
{
function __construct()
{
$this->model = new OrdersModel();
}
}
This will create an instance using the default database (which will be the writer one);
Now if i would like to have a function that would like to call many "SELECT" queries on that model, and would like to direct them to reader nodes, how should i do that?
If i write a function on my model that switches $DBGroup on the model, will that work to change the database on-the-fly?
If its possible at all, how do i return to my "default" (writer) db after that? Do another switch?
