Re: Planner debug views

Qingqing Zhou <zhouqq(dot)postgres(at)gmail(dot)com> writes:
> There are still something bothering me: EXPLAIN is a mixed output with
> original text, rows for RelOptInfo, rows for Paths and possible others
> added later. So we have to use 't as text' to receive each line. To do the
> insertion, we have to further decompose each text line into fields, and
> then do the insertion - seems quite involved with plpgsql programming.

Well, that's only true if we don't expend some effort to make it better.

I could imagine, for instance, that if you specify the EXPLAIN option that
turns on this additional output, the output is no longer just a single
"text" column but is multiple columns. Perhaps one column could be a
key indicating what the other column(s) contain.

Another point is that we decided a long time ago that EXPLAIN's plain-text
output format is not intended to be machine-parsable, and so objecting to
a design on the grounds that it makes machine parsing harder is pretty
wrongheaded. I'd think there is plenty of room for dropping in additional
output data in the non-text output formats. That needs some careful
document-schema design effort, for sure, but it doesn't seem like it would
be particularly hard.

regards, tom lane