On 6/13/07, Gregory Stark <[EMAIL PROTECTED]> wrote:
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.
"...and display it" -- this, I suppose, covers the most frequent needs
(starting from displaying entire plans in some tools and finishing
with odd but useful examples like
http://archives.postgresql.org/pgsql-sql/2005-08/msg00046.php).
You cant do any sort of comparison
between plans, aggregate results, search for plans matching constraints, etc.
Wrong.
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;
XPath can help here. Now almost every language has XML with XPath
support. That's the point, that's why XML is suitable here -- it
simplifies application development (in this specific case ;-) ).
--
Best regards,
Nikolay
---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match
