pub type BackendPidFn = fn() -> u32;Expand description
v7.39 (read01 pgstatfuncs.c) — host-provided identity of the CALLING
connection for pg_backend_pid() / the pg_stat_activity self-join.
The host reads a connection-thread-local set at session start; the
no_std engine just calls through. None (embedded) → pid 1.