Re: backup manifests - Mailing list pgsql-hackers

On Tue, Jan 14, 2020 at 03:35:40PM -0500, Stephen Frost wrote:
> Greetings,
> 
> * David Fetter (david@fetter.org) wrote:
> > On Tue, Jan 14, 2020 at 12:53:04PM -0500, Tom Lane wrote:
> > > Robert Haas <robertmhaas@gmail.com> writes:
> > > > ... I would also expect that depending on an external package
> > > > would provoke significant opposition. If we suck the code into core,
> > > > then we have to keep it up to date with the upstream, which is a
> > > > significant maintenance burden - look at all the time Tom has spent on
> > > > snowball, regex, and time zone code over the years.
> > > 
> > > Also worth noting is that we have a seriously bad track record about
> > > choosing external packages to depend on.  The regex code has no upstream
> > > maintainer anymore (well, the Tcl guys seem to think that *we* are
> > > upstream for that now), and snowball is next door to moribund.
> > > With C not being a particularly hip language to develop in anymore,
> > > it wouldn't surprise me in the least for any C-code JSON parser
> > > we might pick to go dead pretty soon.
> > 
> > Given jq's extreme popularity and compatible license, I'd nominate that.
> 
> I don't think that really changes Tom's concerns here about having an
> "upstream" for this.
> 
> For my part, I don't really agree with the whole "we don't want two
> different JSON parsers" when we've got two of a bunch of stuff between
> the frontend and the backend, particularly since I don't really think
> it'll end up being *that* much code.
> 
> My thought, which I had expressed to David (though he obviously didn't
> entirely agree with me since he suggested the other options), was to
> adapt the pgBackRest JSON parser, which isn't really all that much code.
> 
> Frustratingly, that code has got some internal pgBackRest dependency on
> things like the memory context system (which looks, unsurprisingly, an
> awful lot like what is in PG backend), the error handling and logging
> systems (which are different from PG because they're quite intentionally
> segregated from each other- something PG would benefit from, imv..), and
> Variadics (known in the PG backend as Datums, and quite similar to
> them..).

It might be more fun to put in that infrastructure and have it gate
the manifest feature than to have two vastly different parsers to
contend with. I get that putting off the backup manifests isn't an
awesome prospect, but neither is rushing them in and getting them
wrong in ways we'll still be regretting a decade hence.

Best,
David.
-- 
David Fetter <david(at)fetter(dot)org> http://fetter.org/
Phone: +1 415 235 3778

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