From: Tom Lane <tgl@sss.pgh.pa.us>
To: Jeff Janes <jeff.janes@gmail.com>
cc: Andrew Dunstan <andrew.dunstan@2ndquadrant.com>,
        Jeremy Schneider <schnjere@amazon.com>,
        David Rowley <david.rowley@2ndquadrant.com>,
        Joe Conway <mail@joeconway.com>, Peter Geoghegan <pg@bowt.ie>,
        PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: Should we increase the default vacuum_cost_limit?
In-reply-to: 
 <CAMkU=1zM7sK9Xo2jjwCLj-t+GHR5nQJnPyFUp+puBiFpOQ7aBA@mail.gmail.com>
References: 
 <CAKJS1f_YbXC2qTMPyCbmsPiKvZYwpuQNQMohiRXLj1r=8_rYvw@mail.gmail.com>
 <CAH2-Wz=WQ9ju6sjPF7RcW0g6NPXAenZeC5qVme6uj+eMRw5q2g@mail.gmail.com>
 <241b80ab-7af0-c606-7b2c-b0a5d6be696a@joeconway.com>
 <CAKJS1f_5xofbg0K16MkhQPeCXV6oGCuD2SVcV76OW7ydFDHDkw@mail.gmail.com>
 <df548503-d261-d8c4-97d0-61be6617df41@2ndQuadrant.com>
 <4a068b09-5a6f-e975-07c9-2333fcef0a8a@amazon.com>
 <30411a5b-ef11-71ef-e9ee-4d26ef3fd0c0@2ndQuadrant.com>
 <CAMkU=1zM7sK9Xo2jjwCLj-t+GHR5nQJnPyFUp+puBiFpOQ7aBA@mail.gmail.com>
Comments: In-reply-to Jeff Janes <jeff.janes@gmail.com>
	message dated "Fri, 08 Mar 2019 10:20:19 -0500"
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-ID: <21033.1552068630.1@sss.pgh.pa.us>
Date: Fri, 08 Mar 2019 13:10:30 -0500
Message-ID: <21034.1552068630@sss.pgh.pa.us>
Precedence: bulk

Jeff Janes <jeff.janes@gmail.com> writes:
> Now that this is done, the default value is only 5x below the hard-coded
> maximum of 10,000.
> This seems a bit odd, and not very future-proof.  Especially since the
> hard-coded maximum appears to have no logic to it anyway, at least none
> that is documented.  Is it just mindless nannyism?

Hm.  I think the idea was that rather than setting it to "something very
large", you'd want to just disable the feature via vacuum_cost_delay.
But I agree that the threshold for what is ridiculously large probably
ought to be well more than 5x the default, and maybe it is just mindless
nannyism to have a limit less than what the implementation can handle.

			regards, tom lane