Re: vacuum on table with all rows frozen

On 04/01/2017 09:09 AM, Tom DalPozzo wrote:

Hi,
let's suppose I have a table which after beign populated with only
INSERTs, doesn't receive no more writing queries (neither insert or
update or delete). Only reading queries.
Once all table rows get frozen by (auto)vacuum, will a next (auto)vacuum
scan that table for any reason or does it understand that it would be
useless (as no more rows to mark as forzen and no dead tuples) ?

What version of Postgres?

Don't vacuum all-frozen pages.:

https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=fd31cd265138019dcccc9b5fe53043670898bc9f

That made it into 9.6:
https://www.postgresql.org/docs/9.6/static/release-9-6.html

E.3.3.1.6. VACUUM

Avoid re-vacuuming pages containing only frozen tuples (Masahiko Sawada, Robert Haas, Andres Freund)