Re: machine-readable explain output

On Tue, Jun 16, 2009 at 12:19 PM, Andres Freund<andres(at)anarazel(dot)de> wrote:
> <Startup-Cost>1710.98</Startup-Cost>
> <Total-Cost>1710.98</Total-Cost>
> <Plan-Rows>72398</Plan-Rows>
> <Plan-Width>4</Plan-Width>
> <Actual-Startup-Time>136.595</Actual-Startup-Time>
> <Actual-Total-Time>136.595</Actual-Total-Time>
> <Actual-Rows>72398</Actual-Rows>
> <Actual-Loops>1</Actual-Loops>

XML's not really my thing currently but it sure seems strange to me to
have *everything* be a separate tag like this. Doesn't XML do
attributes too? I would have thought to use child tags like this only
for things that have some further structure.

I would have expected something like:

<join
<scan type=sequential source="foo.bar">
<estimates cost-startup=nnn cost-total=nnn rows=nnn width=nnn></>
<actual time-startup=nnn time-total=nnnn rows=nnn loops=nnn></>
</scan>
<scan type=function source="foo.bar($1)">
<parameters>
<parameter name="$1" expression="...."></>
</parameters>
</scan>
</join>

This would allow something like a graphical explain plan to still make
sense of a plan even if it finds a node it doesn't recognize. It would
still know generally what to do with a "scan" node or a "join" node
even if it is a new type of scan or join.

--
greg
http://mit.edu/~gsstark/resume.pdf