Re: Fast default stuff versus pg_upgrade

Andrew Dunstan <andrew.dunstan@2ndquadrant.com> writes:
> On 06/21/2018 01:18 PM, Tom Lane wrote:
>> I might be OK with a patch that converts *all* of pg_dump's cross-version
>> difference handling code to depend on PQfnumber silently returning -1
>> rather than failing, but I don't want to see it done like that in just
>> one or two places.

> I don't mind changing it. But please note that I wouldn't have done it 
> that way unless there were a precedent. I fully expected to add dummy 
> values to all the previous queries, but when I couldn't find attidentity 
> in them to put them next to I followed that example.

Actually, now that I think about it, there is a concrete reason for the
historical pattern: it provides a cross-check that you did not fat-finger
the query, ie misspell the column alias vs the PQfnumber parameter.  This
gets more valuable the more per-version variants of the query there are.
With the way the attidentity code does it, it would just silently act as
though the column has its default value, which you might or might not
notice in cursory testing.  Getting visible bleats about column number -1
is much more likely to get your attention.

So I'm thinking that the attidentity code is just wrong, and you should
change that too while you're at it.

			regards, tom lane