Re: Better Upgrades

> On 02 Mar 2018, at 01:03, Bruce Momjian  wrote:
> 
> On Tue, Feb  6, 2018 at 01:51:09PM +0100, Daniel Gustafsson wrote:
>>> On 06 Feb 2018, at 01:09, David Fetter  wrote:
>> 
>>> - pg_upgrade is very much a blocker for on-disk format changes.
>> 
>> I wouldn’t call it a blocker, but pg_upgrade across an on-disk format change
>> would be a very different experience from what we have today since it would
>> need to read and rewrite data rather than hardlink/copy.  Definitely not a
>> trivial change though, that I completely agree with.
> 
> Uh, not necessarily.  To allow for on-disk format changes, pg_upgrade
> _could_ rewrite the data files as it copies them (not link), or we could
> modify the backend to be able to read the old format.  We have already
> done that for some changes to data and index types.

Right, that is another option.  I guess we’ll have to wait and see what the
impact will be for the available options when we get there, until there is an
actual on-disk change to reason around it’s a fairly academic discussion.

cheers ./daniel