Bruce,
* Bruce Momjian (bruce@momjian.us) wrote:
> I think the big problem with two-stage pg_upgrade is that the user steps
> are more complex, so what percentage of users are going use the
> two-stage method. The bad news is that only a small percentage of users
> who will benefit from it will use it, and some who will not benefit it
> will use it. Also, this is going to require significant server changes,
> which have to be maintained.
This is where I think we need to be considering a higher-level tool that
makes it easier to run pg_upgrade and which could handle these multiple
stages.
> I think we need some statistics on how many users are going to benefit
> from this, and how are users suppose to figure out if they will benefit
> from it?
If the complexity issue is addressed, then wouldn't all users who use
pg_upgrade in link mode benefit from this..? Or are you thinking we
need to figure out which users really need to have pg_upgrade be faster
from those who don't? The former would be 100% and the latter seems
extremely difficult to determine and not all that useful in the end- not
every user needs SELECT to be faster, but we sure want to make it faster
if we can do so reasonably.
I agree that we need to really consider if the additional complexity is
worth the performance improvement, but I don't think we really have a
gauge as to the complexity level or the ongoing maintenance effort
required, and without that we can't really say if it's too much or not.
Thanks!
Stephen