doc: warn pg_stat_reset() can cause vacuum/analyze problems

The fix is to run ANALYZE.

Discussion: https://postgr.es/m/[email protected],
   https://postgr.es/m/flat/CAKJS1f8DTbCHf9gedU0He6ARsd58E6qOhEHM1caomqj_r9MOiQ%40mail.gmail.com,
   https://postgr.es/m/CAKJS1f80o98hcfSk8j%3DfdN09S7Sjz%2BvuzhEwbyQqvHJb_sZw0g%40mail.gmail.com

Backpatch-through: 10

diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 61add690992eb11f2c2ca40aeea972f6aa0cba3a..ee0f7b4204dd6b6b517b3122bcb14afa2a4a0712 100644 (file)
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -5180,6 +5180,17 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i
     
    
 
+  
+   
+    Using pg_stat_reset() also resets counters that
+    autovacuum uses to determine when to trigger a vacuum or an analyze.
+    Resetting these counters can cause autovacuum to not perform necessary
+    work, which can cause problems such as table bloat or out-dated
+    table statistics.  A database-wide ANALYZE is
+    recommended after the statistics have been reset.
+   
+  
+
   
    pg_stat_get_activity, the underlying function of
    the pg_stat_activity view, returns a set of records