RE: pg_upgrade —link does it remove table bloat

>There is more than one type of statistics though. Stats on the distribution of data is easily recreated with analyze table_name or analyzing the whole >database. What about the stats on how many rows have been inserted or updated since the last (auto)vacuum and that will be used to trigger autovacuum? >Are those set back to zero by an upgrade? I would assume usage counts like how many times an index scan has been done would be reset, but if the >numbers in pg_stat_user_tables like n_tup_upd or n_tup_del are zero'd out during an upgrade, than it would seem like a manual vacuum would always be a >good idea to ensure a table wasn't 99% of the way to needing one and then the stats got reset by upgrading.

I agree @Michael Lewis, thank you for this comment.

I am thinking a vacuum full is what I am going to need.  Or pg_dump / pg_restore. I have tuned auto vacuum after the upgrade to be aggressive, it finishes fine after a couple hours on a large table, statistics look good on the pg_stat_user_tables.  However, when I run the bloat check from the wiki https://wiki.postgresql.org/wiki/Show_database_bloat it still shows bloat.  Thinking it may be left over from before the pg_upgrade and auto vacuum tuning.

Best,

Jason Ralph

From: Michael Lewis <mlewis@entrata.com>
Sent: Thursday, February 13, 2020 1:02 PM
To: Adrian Klaver <adrian.klaver@aklaver.com>
Cc: Jason Ralph <jralph@affinitysolutions.com>; pgsql-general@lists.postgresql.org
Subject: Re: pg_upgrade —link does it remove table bloat