-- Phase 3: cross-backend strictly increasing clock (needs shared_preload_libraries).
-- Two expected files: global.out (preloaded) and global_1.out (not preloaded).
SET client_min_messages = warning;
CREATE EXTENSION IF NOT EXISTS pg_nanotime;
RESET client_min_messages;
SELECT preloaded FROM nanotime_clock_status();
 preloaded 
-----------
 f
(1 row)

SELECT clock_ns_global() IS NOT NULL AS works;
ERROR:  clock_ns_global() requires pg_nanotime to be loaded via shared_preload_libraries
HINT:  Add pg_nanotime to shared_preload_libraries in postgresql.conf and restart the server.
WITH s AS (SELECT g, clock_ns8_global() t FROM generate_series(1, 200000) g),
     d AS (SELECT t, lag(t) OVER (ORDER BY g) p FROM s)
SELECT count(*) AS n, count(*) FILTER (WHERE t <= p) AS not_increasing,
       count(DISTINCT t) AS distinct_values FROM d;
ERROR:  clock_ns_global() requires pg_nanotime to be loaded via shared_preload_libraries
HINT:  Add pg_nanotime to shared_preload_libraries in postgresql.conf and restart the server.
SELECT clock_ns_global() < clock_ns8_global() AND clock_ns8_global() < clock_ns_global() AS shared_counter;
ERROR:  clock_ns_global() requires pg_nanotime to be loaded via shared_preload_libraries
HINT:  Add pg_nanotime to shared_preload_libraries in postgresql.conf and restart the server.
SELECT global_calls > 0 AS counted, global_last_ns IS NOT NULL AS has_last, global_lead_ns < 1000000000 AS lead_small
  FROM nanotime_clock_status();
 counted | has_last | lead_small 
---------+----------+------------
         | f        | 
(1 row)