[development] db_rewrite_sql

[Moshe Weitzman]

> I know I have participated in a discussion like this before, but 
> couldn't find the issue. So here it is again: What about passing a 
> unique identifier along with every call of db_rewrite_sql? Instead of 
> just wrapping db_rewrite_sql() we could also pass $module and $key so we 
> have accurate namespaces for each query. (Or, we could just do it like 
> hook_mail_alter(), but I think there could be namespace conflicts if a 
> module named foo_module's foo_module_key screws with a module named 
> foo's foo_module_key :P)

this was proposed in the original db_rewrite_sql() but didn't get in. We 
called them query hints or somesuch ... We had enough to chew on at that 
time. It is time to try again, as you propose.