Re: [PATCH] Make pg_basebackup configure and start standby [Review]

2013-01-02 10:12 keltezéssel, Magnus Hagander írta:
> On Wed, Jan 2, 2013 at 9:59 AM, Boszormenyi Zoltan <zb(at)cybertec(dot)at
> <mailto:zb(at)cybertec(dot)at>> wrote:
>
> 2013-01-02 01:24 keltezéssel, Tom Lane írta:
>
> Boszormenyi Zoltan <zb(at)cybertec(dot)at <mailto:zb(at)cybertec(dot)at>> writes:
>
> 2013-01-01 17:18 keltezéssel, Magnus Hagander írta:
>
> That way we can get around the whole need for changing memory allocation
> across all the
> frontends, no? Like the attached.
>
> Sure it's simpler but then the consistent look of the code is lost.
> What about the other patch to unify pg_malloc and friends?
> Basically all client code boils down to
> fprintf(stderr, ...)
> in different disguise in their error reporting, so that patch can
> also be simplified but it seems that the atexit() - either explicitly
> or hidden behind InitPostgresFrontend() - cannot be avoided.
>
> Meh. I find it seriously wrongheaded that something as minor as an
> escape_quotes() function should get to dictate both malloc wrappers
> and error recovery handling throughout every program that might use it.
>
>
> Actually, the unification of pg_malloc and friends wasn't dictated
> by this little code, it was just that pg_basebackup doesn't provide
> a pg_malloc implementation (only pg_malloc0) that is used by
> initdb's escape_quotes() function. Then I noticed how wide these
> almost identical functions have spread into client apps already.
>
> I would say this unification patch is completely orthogonal to
> the patch in $SUBJECT. I will post it in a different thread if it's
> wanted at all. The extra atexit() handler is not needed if a simple
> fprintf(stderr, ...) error reporting is enough in all clients.
> As far as I saw, all clients do exactly this but some of them hide
> this behind #define's.
>
>
> Please do keep that one separate - let's avoid unnecessary feature-creep, whether it's
> good or bad features.
>
> I like Magnus' version a lot better than that idea.
>
>
> OK, I will post the core patch building on his code.
>
>
> Thanks.
>
> A bigger issue that I notice with this code is that it's only correct in
> backend-safe encodings, as the comment mentions. If we're going to be
> putting it into frontend programs, how safe is that going to be?
>
> regards, tom lane
>
>
> The question in a different form is: does PostgreSQL support
> non-ASCII-safe encodings at all (or on the client side)? Forgive
> my ignorance and enlighten me: how many such encodings
> exist besides EBCDIC? Is UTF-16 non-ASCII-safe?
>
>
> We do. See http://www.postgresql.org/docs/9.2/static/multibyte.html.
>
> There are quite a few far-eastern encodings that aren't available as server encondings,
> and I believe it's all for this reason.

I see, thanks.

> That said, do we need to care *in this specific case*? We use it in initdb to parse
> config strings, I believe. And we'd use it to parse a conninfo string in pg_basebackup,
> correct?

Correct.

> Perhaps all we need to do is to clearly comment that it doesn't work with non-ascii safe
> encodings, or rename it to indicate that it's limited in this?

If you send a new patch with the function renamed accordingly, I will modify
my code to use it.

Best regards,
Zoltán Böszörményi

--
----------------------------------
Zoltán Böszörményi
Cybertec Schönig & Schönig GmbH
Gröhrmühlgasse 26
A-2700 Wiener Neustadt, Austria
Web: http://www.postgresql-support.de
http://www.postgresql.at/