| From: | David Rowley <david(dot)rowley(at)2ndquadrant(dot)com> |
|---|---|
| To: | PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Should the docs have a warning about pg_stat_reset()? |
| Date: | 2019-03-26 12:53:42 |
| Message-ID: | CAKJS1f8DTbCHf9gedU0He6ARsd58E6qOhEHM1caomqj_r9MOiQ@mail.gmail.com |
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| Lists: | pgsql-hackers |
As I mentioned in [1], I've had a few cases recently about auto-vacuum
not working. On the other thread, it was all about auto-vacuum being
configured to run too slowly. The other culprit for auto-vacuum not
working is when people periodically use pg_stat_reset().
The problem with pg_stat_reset() is that it zeros n_dead_tup and
n_mod_since_analyze. If say a user resets the stats on a monthly
basis then this can mean that tables that normally receive an
auto-vacuum any less frequently than once per month could never
receive an auto-vacuum... at least not until an anti-wraparound vacuum
gets hold of it.
The best I can think to do to try and avoid this is to put a giant
WARNING in the docs about either not using it or to at least run
ANALYZE after using it.
Does anyone else think this is a problem worth trying to solve?
--
David Rowley http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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