Re: EXPLAIN omits schema?

"Joshua D. Drake" <jd(at)commandprompt(dot)com> writes:

>> I agree. XML seems like a fairly natural fit for this. Just as people should
>> not try to shoehorn everything into XML, neither should they try to shoehorn
>> everything into a relational format either.
>>
>> Now all we need is an XML schema for it ;-)
>
> Well I am not a big fan of XML but it certainly seems applicable in this
> case.

I'm not a fan either so perhaps I'm biased, but this seems like a good example
of where it would be an *awful* idea.

Once you have an XML plan what can you do with it? All you can do is parse it
into constituent bits and display it. You cant do any sort of comparison
between plans, aggregate results, search for plans matching constraints, etc.

How would I, with XML output, do something like:

SELECT distinct node.relation
FROM plan_table
WHERE node.expected_rows < node.actual_rows*2;

or

SELECT node.type, average(node.ms/node.cost)
FROM plan_table
GROUP BY node.type;

--
Gregory Stark
EnterpriseDB http://www.enterprisedb.com