are connections to Database http based or tcp based.
Are jdbc of spring-boot application to postgressql http method connections based or tcp based connections.
Although JDBC connections to PostgreSQL utilize a URL (Uniform Resource Locator), they are not using the HTTP protocol. They don't use TCP port 80, either, if that's what you were asking; they use the default port of 5432 unless you have configured your Postgre server to use a different port. You can find the details here.
You would usually expect connections that aren’t used for transportation of hypertext to use something different than Hyper-Text Transport Protocol. The usual way to transport other data with some control over whether it has arrived would probably be a protocol built on top of Transport Control Protocol.
JDBC (Java Database Connectivity) connections in a Spring Boot application to a PostgreSQL database are TCP-based connections, not HTTP-based. JDBC uses the PostgreSQL protocol, which operates over TCP/IP, to communicate with the database server.
HTTPis an application level protocol and usually usesTCP/IPas underlying transport protocol, so even databases like CouchDB that useHTTPalso useTCP/IP.