Junction table or denormalize?

I'm using MariaDB. I'm designing a simple application that can send notifications to subscribers for when certain websites they've subscribed to have been updated. A user can be subscribed to several different sites and multiple users can subscribe to same site. So both tables are independent in a vacuum. Simple schema for both, just a 1. sites table containing ids and urls 2. subscribers table containing ids and phone#s My tentative flow for efficiency and scalability is something like the following 1. Cron job every hour that gets all Sites from sites table 2. Makes parallel web requests for all sites 3. Detect sites that have been changed (this will be compared against to another column in sites table) 4. Alert users of changed sites which sites got updated (prob also send alerts in parallel) Is introducing a junction table even necessary for this? I feel like it'd introduce complexity bc I'd have to join on that everytime and update that everytime a change has been made to either subscribers table. Or.. should I just denormalize.. Seems like sites is kind of the "common denominator" here (i.e. I'll always check if EVERY site has changed, but I don't necessarily need all subscribers) So given ^, I was thinking of maybe just adding a Sites.subsriber_ids field.. Or..should I just go for a NoSQL approach? Any thoughts and recommendations ? Thanks! CREATE TABLE provsub ( provider_id int(11) NOT NULL, subscriber_id int(11) NOT NULL, created timestamp NOT NULL DEFAULT current_timestamp(), updated timestamp NOT NULL DEFAULT current_timestamp() ON UPDATE current_timestamp(), PRIMARY KEY (provider_id,subscriber_id), KEY subscriber_id (subscriber_id), CONSTRAINT provsub_ibfk_1 FOREIGN KEY (provider_id) REFERENCES providers (id), CONSTRAINT provsub_ibfk_2 FOREIGN KEY (subscriber_id) REFERENCES subscribers (id) ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 |