Is it possible to get information that a record has appeared in the database?

Question

PostgreSQL

Petya sent a message to Vasya. How does Vasya know that he has received a message, should the server send requests after a certain time, or can the database itself notify that Vasya has a new record in the table? I can only suggest that the server can make queries to the database to check for new records and then send them to the client, but I don't think this is the right way. I did not work with the database, so far I only wrote / read from there. Thank you!

Answer 1

PostgreSQL has a notification mechanism . An example of usage in Go.

Answer 2

I did not work with the database, so far I only wrote / read from there.

That's when you write a new message there, then process it as an event.

Answer 3

Why not just send a notification via WebSocket after adding an entry to the database? It is not necessary to interrogate just like that in the database.
Pseudocode:

func onMessage(message Message) {
    db.Save(message)
    chat.Notification(message)
}

Answer 4

Firstly, there are triggers in the database.
Secondly, for high loads it is not done this way. Not through a DB, and through MQ.

Answer 5

depends on tasks, but it is worth looking towards RabbitMQ if you only need to forward messages