Re: libpq debug log

I wrote:
> Or we could rethink the logic. It's not quite clear to me, after
> all this time, why getRowDescriptions() et al are allowed to
> move inStart themselves rather than letting the main loop in
> pqParseInput3 do it. It might well be an artifact of having not
> rewritten the v2 logic too much.

After studying this further, I think we should apply the attached
patch to remove that responsibility from pqParseInput3's subroutines.
This will allow a single trace call near the bottom of pqParseInput3
to handle all cases that that function processes.

There are still some cowboy advancements of inStart in the functions
concerned with COPY processing, but it doesn't look like there's
much to be done about that. Those spots will need their own trace
calls.

BTW, while looking at this I concluded that getParamDescriptions
is actually buggy: if it's given a malformed message that seems
to need more data than the message length specifies, it just
returns EOF, resulting in an infinite loop. This function apparently
got missed while converting the logic from v2 (where that was the
right thing) to v3 (where it ain't). So that bit needs to be
back-patched. I'm tempted to back-patch the whole thing though.

regards, tom lane