Should I re-use a database connection or create new collections while closing old ones? social media

this is for a social media with constant requests for new posts, checking is someone is following, getting comments, ect. i wont specify which language as it doesnt really matter but, currently in my code i - make connection - get/do what i want - close and then repeat instead should I use a system where i make a connection, and then do thinsg from that while sometimes running an update? thanks!