Re: Misdesigned command/status APIs for parallel dump/restore

I wrote:
> In the attached patch for this, I took a middle ground of separating out
> the command and status string building and parsing functions. There isn't
> presently any provision for letting archive format modules override these,
> but that could easily be added if we ever need it. Meanwhile, this saves
> about 100 lines of rather messy code.

Attached are two versions of this patch. The first is against current
HEAD (i.e., rebased over e652273e073566b6) and the second is additionally
over the patch I proposed at <6814(dot)1464893855(at)sss(dot)pgh(dot)pa(dot)us>, resolving
the merge conflicts between them.

Since this is only refactoring, and doesn't (I think) fix any bugs,
I'm setting it aside till the next commitfest.

regards, tom lane