From: =?ISO-8859-1?Q?Torsten_Z=FChlsdorff?= <foo@meisterderspiele.de>
Subject: Re: Using more tha one index per table
Date: Sat, 24 Jul 2010 14:57:38 +0200
Organization: A noiseless patient Spider
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To: pgsql-performance@postgresql.org

Craig James schrieb:

>>> The problem is that Google ranks pages based on inbound links, so
>>> older versions of Postgres *always* come up before the latest version
>>> in page ranking.
>>
>> Since 2009 you can deal with this by defining the canonical-version.
>> (http://googlewebmastercentral.blogspot.com/2009/02/specify-your-canonical.html) 
>>
> 
> This is a really cool feature, but it's not what we need.  The 
> "canonical" refers to the URL, not the web page.  It's only supposed to 
> be used if you have multiple URLs that are actually the *same* page; the 
> "canonical" URL tells Google "use only this URL for this page."
> 
> But in our case, the Postgres manuals for each release have different 
> URLs *and* different content, so the "canonical URL" isn't the right 
> solution.

This is true, but the content is allowed to change "a little". Of course 
their is no percentage of allowed changes. But it can be quite much. 
I've used this feature for some clients, which push their content into 
very different websites and it does work.
Most of the content of the documentation doesn't change much between the 
releases. In most cases the canonical will work the way i suggest.

In case of big changes even the recommandation of using a "current" 
version won't work. Its true that Google ranks pages based on inbound 
links. But there are more than 200 other factores, which influence the 
rankings. Most people do not know, that changing most of a sites content 
makes the inbound links for a long time useless. After big changes in 
the documentation the "current" entry will be droped for some monthes 
and the old entries will appear. But note, that every single site of the 
documentation is ranked for itself. From my experience i would expect 
the canonical-version with better results, than the current-version.

But the canonical is not the best solution in my opinion. I often edit 
the urls of some documentations, because i need it for a special 
postgresql version. The documentation clearly misses a version-switch. 
Combined with an big note, that the current displayed documentation is 
not the one of the current postgresql-version, this will be the best 
compromiss in my opinion.

Greetings from Germany,
Torsten