From: Jacob Fugal <lukfugl@...>
Date: 2006-07-01T01:47:44+09:00
Subject: Re: [RubyGems] Rational about the Gem package format?

On 6/30/06, transfire@gmail.com <transfire@gmail.com> wrote:
> I was just wondering about the rational behind the format of gem
> packages. It seems rather odd that the package is a tar of
>
>   data.tar.gz
>   metadata.gz
>
> Why not just have the metadata stored in with the data and not worry
> about double layers? The only advantage I can figure is that it is
> possilble to extract the metadata without uncompressing the eniter
> package. Okay, but can't a tar/gzip lib or tool do that anyway? Is
> there some other reason?

I think it's for the reason you mentioned. tar can extract specific
files out of the package without needing to extract the whole package,
but -- if I recall correctly -- the gzip compression format still
requires that the whole package be decompressed before the files could
be extracted. So compressing the metadata and actual data separately
means you only need to decompress the metadata if that's all you're
after.

Jacob Fugal