Sending SIGUSR1 to bgphist will show database queue on each address family like this
Stats: ipv4u(465794,122917) ipv4m(0,0) ipv4lu(0,0) vpnv4u(200681,10) ipv6u(0,0) ipv6lu(13251,0) vpnv6u(0,0) l2vpn(342,0)