Adding pg_wait_sampling

Author: andyatkinson

pg_wait_sampling_queries.sql

@@ -0,0 +1,45 @@
+-- Querying pg_wait_sampling_history after
+-- enabling the extension
+
+-- Views:
+-- pg_wait_sampling_profile
+-- pg_wait_sampling_history
+
+SELECT * FROM pg_wait_sampling_history LIMIT 1;
+-- pid
+-- ts (timestamp)
+-- event_type
+-- event
+-- queryid
+--
+
+-- Wait events by process type (event_type)
+-- Event types (Client, Activity)
+-- Events: ClientRead, AutoVacuumMain
+SELECT
+    pid,
+    event_type,
+    event,
+    count(*)
+FROM
+    pg_wait_sampling_history
+WHERE
+    ts > now() - interval '1 hour'
+GROUP BY
+    pid,
+    event_type,
+    event
+ORDER BY
+    count(*) DESC;
+
+
+-- https://akorotkov.github.io/blog/2016/03/25/wait_monitoring_9_6/
+-- For queries we probably care most about Lock (heavyweight), LWLock (lightweight)
+-- For events buffer_content, transactionid
+
+
+-- Default is 1s, can increase the sampling frequency
+pg_wait_sampling.sample_interval = '10ms'
+
+--- Can change the history, default 100
+pg_wait_sampling.history_size = 1000