Re: block-level incremental backup

On Tue, Sep 3, 2019 at 8:00 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Ibrar Ahmed <ibrar(dot)ahmad(at)gmail(dot)com> writes:
> > +1 using the library to tar.
>
> Uh, *what* library?
>

I was just replying the Robert that he said

"But I think there must be a reason why tar libraries exist,
and I don't want to write a new one."

I said I am ok to use a library "what he is proposing/thinking",
but explained to him that TAR is the most simpler format that
why PG has its own code.

> pg_dump's pg_backup_tar.c is about 1300 lines, a very large fraction
> of which is boilerplate for interfacing to pg_backup_archiver's APIs.
> The stuff that actually knows specifically about tar looks to be maybe
> a couple hundred lines, plus there's another couple hundred lines of
> (rather duplicative?) code in src/port/tar.c. None of it is rocket
> science.
>
> I can't believe that it'd be a good tradeoff to create a new external
> dependency to replace that amount of code. In case you haven't noticed,
> our luck with depending on external libraries has been abysmal.
>
> Possibly there's an argument for refactoring things so that there's
> more stuff in tar.c and less elsewhere, but let's not go looking
> for external code to depend on.
>
> regards, tom lane
>

--
Ibrar Ahmed