Yes, we will recommend you to fetch this instrument list at the day start and store it at your end, as it doesn't change throughout the day. You fetch the same on the next trading day.
Lets say, I have N instrucments in my wtch list and want to get there update price using WebSocket streaming. So is there any limitation on websocket open connection?
You can subscribe up to 3000 instruments/shares in a single WebSocket connection, and for single API key you can have 3 WebSocket connection, so you can stream maximum of 9000 shares for a API key.
Also want to check same for WebSocket streaming?
Websocket streaming don't have instrument list. You will have to fetching instrument list using Instrument API call.