Unlike pq, we choosed URL style for DSN. It's difficult to write path in config.
We need to write %2F instead of /.

From v1.5, I want to promote Connector interface instead of DSN. DSN is too complicated already.

pq also have URL style for DSN, you can check it here: https://godoc.org/github.com/lib/pq

example from docs:

connStr := "postgres://pqgotest:password@localhost/pqgotest?sslmode=verify-full"

pq also have URL style for DSN

Is it be able to specify certificate path easily, without %2F?

I extracted the code from pq project to test it out and I see that you don't need to specify %2F in path. Here is the code to test:

package main

import "fmt"
import nurl "net/url"
import "strings"

func main() {
	url := "postgres://bob:secret@1.2.3.4:5432/mydb?sslrootcert=/test/root.crt"

	u, _ := nurl.Parse(url)

	var kvs []string
	escaper := strings.NewReplacer(` `, `\ `, `'`, `\'`, `\`, `\\`)
	accrue := func(k, v string) {
		if v != "" {
			kvs = append(kvs, k+"="+escaper.Replace(v))
		}
	}

	q := u.Query()
	for k := range q {
		accrue(k, q.Get(k))
	}

	fmt.Println(q)

}

Result:

map[sslrootcert:[/test/root.crt]]

Playground: https://play.golang.org/p/FxM9doANUnI