Re: [RFC][PATCH]: CRC32 is limiting at COPY/CTAS/INSERT ... SELECT + speeding it up

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От Andres Freund
Тема Re: [RFC][PATCH]: CRC32 is limiting at COPY/CTAS/INSERT ... SELECT + speeding it up
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Msg-id 201005210711.35247.andres@anarazel.de
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Ответ на Re: [RFC][PATCH]: CRC32 is limiting at COPY/CTAS/INSERT ... SELECT + speeding it up  (Robert Haas <robertmhaas@gmail.com>)
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On Friday 21 May 2010 05:40:03 Robert Haas wrote:
> On Thu, May 20, 2010 at 4:27 PM, Andres Freund <andres@anarazel.de> wrote:
> > I looked a bit around for faster implementations of CRC32 and found one
> > in zlib. After adapting it (pg uses slightly different computation (non-
> > inverted)) I found that it increases the speed of the CRC32 calculation
> > itself 3 fold.
> 
> But zlib is not under the PostgreSQL license.
Yes. But:
1. the zlib license shouldn't be a problem in itself - pg_dump also already 
links to zlib
2. I planned to ask Mark Adler whether he would support relicising those bits. 
I have read some other discussions where he was supportive of doing such a 
thing
3. Given that idea was posted publically on the usenet it is not hard to 
produce an independent implementation.

So I do not see any big problems there... Or am I missing something?

Greetings,

Andres

/* zlib.h -- interface of the 'zlib' general purpose compression library version 1.2.2, October 3rd, 2004
 Copyright (C) 1995-2004 Jean-loup Gailly and Mark Adler
 This software is provided 'as-is', without any express or implied warranty.  In no event will the authors be held
liablefor any damages arising from the use of this software.
 
 Permission is granted to anyone to use this software for any purpose, including commercial applications, and to alter
itand redistribute it freely, subject to the following restrictions:
 
 1. The origin of this software must not be misrepresented; you must not    claim that you wrote the original software.
Ifyou use this software    in a product, an acknowledgment in the product documentation would be    appreciated but is
notrequired. 2. Altered source versions must be plainly marked as such, and must not be    misrepresented as being the
originalsoftware. 3. This notice may not be removed or altered from any source distribution.
 
 Jean-loup Gailly jloup@gzip.org Mark Adler madler@alumni.caltech.edu

*/



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