Statistics are lost after failover-CodePudding

Following a failover, the statistics are reset to 0 on the new primary in the pg_stat_user_tables view.

 relname | n_tup_ins | n_tup_upd | n_tup_del | n_live_tup | n_dead_tup | last_autovacuum | last_autoanalyze | n_mod_since_analyze
--------- ----------- ----------- ----------- ------------ ------------ ----------------- ------------------ ---------------------
 foo     |         0 |         0 |         0 |          0 |          0 |                 |                  |                   0
(1 row)

If modifications are made on a tables (update/delete/insert) and the vacuum was not executed before the FO, the planner's statistics won't be up to date. Is there an easy way to deal with this problem?

CodePudding user response：

Those are not the planner's statistics, those are the autovac launcher's statistics. The planner's statistics are in pg_statistic and friends, which are logged transactional tables and so are not lost on FO.

If a table was just about to be auto-analyzed before the FO, then it could undergo twice the normal activity between auto-analyzes. So yes, the planner stats can become slightly more out of date than they usually are. That generally won't be a problem, but if you are worried you can do a manual ANALYZE per db, or use vacuumdb to do it.