Re: generic explain options v3

Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> Ugh. I took a look at this and it turns out that there are some
> tentacles. It doesn't seem very sane to actually do anything with a
> list of DefElem nodes, so we really need to parse that list and
> convert it to a more sensible format right away (this also seems
> important for proper error checking).

Yeah, the standard approach is to convert it into a group of values
at the start of execution of the utility command.

> The obvious solution to that is to create the ExplainState sooner,
> back up at the ExplainQuery level. If we do that, though, then
> ExplainState will need to become a public API, because
> contrib/auto_explain calls ExplainPrintPlan().

Well, if we add any more options to EXPLAIN then auto_explain may well
be interested in them, so I'm not sure this is bad. The alternative
is to keep adding retail parameters to the public functions.

> And if we do that,
> then probably we should declare it in include/nodes/execnodes.h and
> make it a node type...

No, just a struct declared in commands/explain.h. There's no reason
for it to be part of the Node system.

regards, tom lane