Date: Mon, 27 Aug 2012 09:46:41 -0400
From: Bruce Momjian <bruce@momjian.us>
To: Peter Eisentraut <peter_e@gmx.net>
Cc: Josh Kupershmidt <schmiddy@gmail.com>, Greg Smith <greg@2ndquadrant.com>,
	Euler Taveira de Oliveira <euler@timbira.com>, pgsql-docs@postgresql.org
Subject: Re: somewhat wrong archive_command example
Message-ID: <20120827134641.GD11088@momjian.us>
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On Sun, Aug 26, 2012 at 11:43:45PM -0400, Peter Eisentraut wrote:
> I'm a little bit worried about this whole discussion.  We have half a
> dozen supposed experts working on a 10-line shell script to do WAL
> archiving, and there is still
> 
> - disagreement
> - uncertainty
> - bugs
> 
> How is a normal user supposed to do this?
> 
> That aside, I disagree with the premise for this script.  It doesn't do
> anything more than the typical inline examples we give.  The additional
> error reporting could be considered useful, but cp is perfectly capable
> of reporting these errors itself, and getting in the way of that just
> loses information and introduces race conditions.  But if we are going
> to provide a separate shell script, we should at least offer some
> additional value, such as addressing the partial copy problem.  But I
> think that's not very easy to do in portable shell.

I thought the idea was just to show what a shell script might look like 
--- we could say it does the same as a single-line copy, but then people
could improve it, or we could add a comment to show how people could
improve it.

I am actually unclear how the partial copy problem would not be fixed by
just using cp without -i < /dev/null.

> I think what we should do is write a wrapper program in C that covers
> all the bases, support all platforms, and supports a handful of the most
> commonly used copy methods (cp, scp, etc. + compression).  Then everyone
> can just use that and doesn't have to figure all these things out from
> scratch every time.

I doubt it would work because people like the flexibility of shell
scripts.

-- 
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + It's impossible for everything to be true. +