SSO, Pathauto, and Domain_prefix are not compatible [#947298]

The issue #717064: Clarify Domain Access and SSO instructions points out on comment #23 the following appears in the Domain Prefix documentation:

If you must prefix all tables, do not set $db_prefix as an array.  This module should still work if $db_prefix = 'string_'.

And the commenter goes on to note that this means these modules conflict. Below I describe why this can be a real problem...

Domain Access + SSO Domain Access + Pathauto

Domain Access + SSO	Domain Access + Pathauto
I have three domains that share some content and definitely share one set of credentials. We sold the client on the idea of having one login for multiple sites. The trick to make this work with Domain Access is to have a non-domain-access site be the "master" site for use with the SSO module (http://drupal.org/project/sso). This trick uses $db_prefix to share access to the sessions table. See http://www.bleen.net/blog/domain-access-sso for more info. The following is REQUIRED to get Domain Access to recognize a logged-in user across multiple domains. `$db_prefix = array( 'default' => '', // <-- If your existing db uses a prefix, enter that prefix here instead of '' 'authmap' => 'controller_database.', // <-- note the '.' 'sessions' => 'controller_database.', 'users' => 'controller_database.', );`	Lets say you have multiple sites that share "some information" (like job openings, and featured news articles) but are about separate companies. Each website has different pages for "About Us." And you create these three separate nodes on each domain: www.domainA.com/about-us www.domainB.com/about-us-0 www.domainC.com/about-us-1 According to the following issues: #665856: Can I use Domain Access with Path Auto and use same Alias between 2 domains? #664174: Pathauto question #300454: Inter domain linking We can make pathauto behave by prefixing the system's url_alias table.

I have three domains that share some content and definitely share one set of credentials. We sold the client on the idea of having one login for multiple sites. The trick to make this work with Domain Access is to have a non-domain-access site be the "master" site for use with the SSO module (http://drupal.org/project/sso).

This trick uses $db_prefix to share access to the sessions table. See http://www.bleen.net/blog/domain-access-sso for more info. The following is REQUIRED to get Domain Access to recognize a logged-in user across multiple domains.

$db_prefix = array(
'default' => '', // <-- If your existing db uses a prefix, enter that prefix here instead of ''
'authmap' => 'controller_database.', // <-- note the '.'
'sessions' => 'controller_database.',
'users' => 'controller_database.',
);

Lets say you have multiple sites that share "some information" (like job openings, and featured news articles) but are about separate companies. Each website has different pages for "About Us." And you create these three separate nodes on each domain:

According to the following issues:

#665856: Can I use Domain Access with Path Auto and use same Alias between 2 domains?
#664174: Pathauto question
#300454: Inter domain linking

We can make pathauto behave by prefixing the system's url_alias table.

Errors

Once I prefixed this table on all domains, I got the following errors (which is confirmed on multiple occasions on issue #717064 mentioned up above).

Type: Access Denied
User: Anonymous
Message: singlesignon/claim
Severity: Warning

What is happening?

I enabled Domain Access and SSO and got them working
I enabled Pathauto and was happy
I created three separate nodes on three separate domains and was not happy with pathauto
I enabled one Domain Prefix table to "make" pathauto "domain" aware
The Domain Prefix's way to use $db_prefix conflicts with SSO's $db_prefix Array and creates scary Access Denied messages

What are possible solutions?

Create a PathAuto_Domain module to circumvent this common practice
Notify users on the homepage of Domain Access that SSO, Domain Access, and Pathauto do have some incompatibilities
Make Domain Prefix use something other than $db_prefix to work