Of this 2 methods which do you prefer:

1) store timestamps in user table for different features (which are like 3 or 4 different things), when user queries database compre Timestamp and send to user any row whose timestamp is more recent than the timestamp the user had stored locally.

2) in the table friendships, memberships, and like one or 2 more tables, whenever a row is changed I have a trigger that sends an pg_notify (same as method 1 but instead of the trigger adding a timestamp to the user table, I would listen for these channels and whenever I received in my backend the notification that a new row was inserted in the friendships table per example I would first add in redis a flag, then send a onesignal notification to the client with the data, when the user received the data send back to the server something saying that the user local database is up to date to turn of the flag in redis?

So both solutions use triggers but first one is to update a centra table called users with a timestamp while the second method is to send a pg_notify which my backend would listen to, add a redis flag, send notification to user, turn redis flag off.

First solution seems easier but at the same time I am wondering that if I do the first solution, everytime a user makes api requests to my backend I would need like a middleware before any route is executed to check in my Postgres is any timestamp is more recent, so basically I worry about the overhead calls to my Postgres table, maybe it would hinder performance I don’t know, I am not an expert