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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 10:54:07
Message-ID: 50E411CF.20802@cybertec.at (view raw or flat)
Thread:
Lists: pgsql-hackers
2013-01-02 10:37 keltezéssel, Boszormenyi Zoltan írta:
> 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.

Attached is the quotes-v2 patch, the function is renamed and
the comment is modified plus the pg_basebackup v21 patch
that uses this function.

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/


Attachment: pg_basebackup-v21.patch
Description: text/x-patch (15.2 KB)
Attachment: quotes-v2.patch
Description: text/x-patch (3.9 KB)

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Subject: [PATCH] Factor out pg_malloc and friends into port code
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Subject: Re: [PATCH] Make pg_basebackup configure and start standby [Review]

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