Re: -Wformat-zero-length

On 8/8/12 5:29 PM, Alvaro Herrera wrote:
> I think those 14 is a bit of a made-up number.  Several of those steps
> are about building pg_upgrade, not actually using it.  And there are
> some that are optional anyway.

Compare the pg_upgrade instructions

http://www.postgresql.org/docs/9.2/static/pgupgrade.html

to the old pg_dump-based upgrade instructions that we used to give people:

http://www.postgresql.org/docs/8.4/static/install-upgrading.html

They are about the same in complexity (the pg_dump approach didn't talk 
about updating statistics or removing the old cluster, so it has less 
steps).

So I don't think the number of steps is a problem at all.  They could be 
simplified a little bit more, of course.

What's more of a problem in my mind is the "unknown unknowns" in 
pg_upgrade's approach.  In the pg_dump/restore approach, you knew that 
if the dump succeeded and the restore succeeded, your new database was 
very likely good.  The only problem could be that pg_dump forgot to dump 
something altogether, or that there is a general problem in executing 
SQL commands, both of which would be obvious problems.  With pg_upgrade, 
however, you never know whether your new instance is good.  You could 
notice problems months later.  That's a really tough proposition.

> Another thing worth considering is to have pg_upgrade init, stop and
> start clusters as necessary instead of requesting the user to do it.
> I think this is two less steps.

Then you'd need to expose the entire pg_ctl shutdown mode logic through 
pg_upgrade, which might not make things simpler.

> I wonder if things would be facilitated by having a config file for
> pg_upgrade to specify binary and PGDATA paths instead of having awkward
> command line switches.

If you want to do that, why not write a shell script?  That's what they 
are for.