Re: reloption to prevent VACUUM from truncating empty pages at the end of relation

Andrew Dunstan <andrew.dunstan@2ndquadrant.com> writes:
> On 3/1/19 2:14 PM, Tom Lane wrote:
>> Indeed, but I'm not sure that the use-cases are the same.  In particular,
>> unless somebody has done some rather impossible magic, it would be
>> disastrous to apply DISABLE_INDEX_CLEANUP as a reloption, because then
>> it would be persistent and you'd never get a real vacuum operation and
>> soon your disk would be full.  Permanently applying truncation disabling
>> seems less insane.

> You could allow an explicitly set command option to override the reloption.
> It's important for us to be able to control the vacuum phases more. In
> particular, the index cleanup phase can have significant system impact
> but often doesn't need to be done immediately.

I'm not objecting to having a manual command option to skip index cleanup
(which basically reduces to "do nothing but tuple freezing", right?
maybe it should be named/documented that way).  Applying it as a reloption
seems like a foot-gun, though.

            regards, tom lane