Fixes #3, fixes #4

Adds tested replica telemetry readings from slaves
Adds wait event details reports
Bumps up version numbers for new release

META.json

@@ -1,7 +1,7 @@
 {
    "name": "pgtelemetry",
    "abstract": "Useful monitoring and metrics views for PostgreSQL",
-   "version": "0.2.0",
+   "version": "1.0.0",
    "maintainer": [ "Chris Travers <christravers@adjust.com>" ],
    "license": {
       "PostgreSQL": "http://www.postgresql.org/about/licence"
@@ -10,7 +10,7 @@
       "pgtelemetry": {
          "file": "extension/pgtelemetry-HEAD.sql",
          "docfile": "doc/pgtelemetry.html",
-         "version": "0.2.0",
+         "version": "1.0.0",
          "abstract": "Useful monitoring and metrics for PostgreSQL"
       }
    },
@@ -24,7 +24,8 @@
       "runtime": {
         "requires": {
            "PostgreSQL": "9.6.0",
-           "pg_stat_statements": 0
+           "pg_stat_statements": 0,
+           "plpgsql": 0
         }
       }
    },

extension/pgtelemetry--0.2--1.0.sql

@@ -0,0 +1,41 @@
+
+create function wal_telemetry_create_or_select_record()
+returns pg_telemetry_wal_log language plpgsql as
+$$
+declare log_entry pg_telemetry_wal_log;
+begin
+    if pg_is_in_recovery() then
+       select * into log_entry from pg_telemetry_wal_log order by current_epoch desc limit 1;
+    else
+       insert into pg_telemetry_wal_log
+       select extract('epoch' from now()), now(),
+                   pg_current_xlog_location() end as wal_location
+       WHERE NOT is_replica()
+       returning * into log_entry;
+    end if;
+    return log_entry;
+end;
+$$;
+
+create function wal_telemetry() returns table (
+   current_epoch numeric, last_epoch numeric, secs_elapsed numeric,
+   current_lsn pg_lsn, last_lsn pg_lsn, bytes_elapsed numeric,
+   bytes_per_sec numeric
+) language sql as $$
+WITH insert_record AS 
+   select c.run_time as current_epoch, l.run_time as last_epoch,
+          c.run_time - l.run_time as secs_elapsed,
+          c.lsn as current_lsn, l.lsn as last_lsn,
+          c.lsn - l.lsn as bytes_elapsed,
+          (c.lsn - l.lsn)::numeric / (c.run_time - l.run_time) as bytes_per_sec
+     FROM wal_telemetry_create_or_select_record() c,
+  lateral (select * from pg_telemetry_wal_log where run_time < c.run_time
+            order by run_time desc limit 1) l;
+$$ set search_path from current;
+
+select wal_telemetry();
+
+CREATE VIEW waiting_queries_reason_details AS
+select wait_event_type, wait_event, count(*) from pg_stat_activity
+ WHERE wait_event is not null
+ GROUP BY wait_event_type, wait_event;`