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

From: Boszormenyi Zoltan <zb(at)cybertec(dot)at>
To: Magnus Hagander <magnus(at)hagander(dot)net>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: [PATCH] Make pg_basebackup configure and start standby [Review]
Date: 2013-01-02 09:37:21
Message-ID: 50E3FFD1.7000904@cybertec.at (view raw or flat)
Thread:
Lists: pgsql-hackers
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/

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