Re: FDW API: don't like the EXPLAIN mechanism

Andrew Dunstan <andrew@dunslane.net> writes:
> On 02/19/2011 11:07 PM, Tom Lane wrote:
>> However, it occurs to me that as long as we're passing the function the
>> ExplainState, it has what it needs to add arbitrary EXPLAIN result
>> fields.

> If we allow the invention of new explain states we'll never be able to 
> publish an authoritative schema definition of the data. That's not 
> necessarily an argument against doing it, just something to be aware of. 
> Maybe we don't care about having EXPLAIN XML output validated.

I thought one of the principal arguments for outputting XML/etc formats
was exactly that we'd be able to add fields without breaking readers.
If that's not the case, why did we bother?
        regards, tom lane