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Re: join on multiple field

From: Eric Blake
Subject: Re: join on multiple field
Date: Mon, 13 Feb 2012 06:37:42 -0700
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0) Gecko/20120131 Thunderbird/10.0

On 02/12/2012 08:40 PM, Peng Yu wrote:
> Hi,
> It seems that 'join' only allow joining on 1 field.

Correct, that's the POSIX-specified behavior.

> It will be very
> useful to allow multiple field join.

Can't you already do this with awk?

> Is anybody in the develop team
> interested in adding such a feature in join?

Not really, unless _you_ want to submit the patches.  It's very hard to
justify bloating 'join' to do something that 'awk' can already do, since
it is easier to find a machine with a solution that works now with awk
than it is to find a machine with a new version of coreutils installed
with your proposed extension to 'join'.


The same comments from that thread still apply:

> Send patches. (send unified diffs, please -- i.e. diff -u format) If your
> changes fix bugs, the bar is quite low in that I don't need much more
> than to understand what the original problem was.  However, it helps
> a lot if you can give me enough information to reproduce the problem.
> On the other hand, if you're adding new features, please follow the
> guidelines below:
>   - convince me that this is a useful change/addition
>       (if you're adding yet another option to ls, the above is pretty hard)
>   - convince other people of the same thing
>       One way to do that is to send mail to address@hidden

[the mail archive munged that; it would be address@hidden]

>       (aka the gnu.utils.bug news group) including as much description
>       and justification as you can.  Based on the feedback that generates,
>       you may be able to convince me.

Eric Blake   address@hidden    +1-919-301-3266
Libvirt virtualization library

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