On Saturday, March 28, 2015 at 7:31:49 AM UTC-7, Janko Marohnić wrote:
>
> Would it be a performance hit to run that ASTTransformer?
>
Yes.
> Yes, I agree that if it were to be implemented on #where, it should be
> implemented on #order and others. It just feels so natural for me that it
> works this way, especially coming from ActiveRecord :)
>
It doesn't feel natural to me. If I use an unqualified identifier in ruby,
I expect an unqualified identifier in SQL. If I want a qualified
identifier in SQL, I use a qualified identifier in ruby. If I want to
automatically qualify unqualified identifiers, I use Dataset#qualify.
> As an outside user of the Quiz#search method, I have to remember that it
> does a join (it could have also been implemented as a subquery instead of a
> join). So when I'm using Quiz in controller, I have to remember to throw in
> #qualify before the #search (so that e.g. "created_at" column isn't
> ambiguous):
>
If you want to be safe, just like in SQL, you need to manually qualify each
column (or use Dataset#qualify to do so automatically).
> Quiz.newest.in(category).qualify.search(query)
>
> I don't know if maybe I have a wrong approach.
>
You aren't returning any columns from the questions table, and you are
joining to a 1-n table and using distinct, so I think it would be better to
use a subquery, assuming you are using a database with a decent subquery
optimizer. If you use a subquery, you don't need to worry about qualifying
the columns.
def newest
reverse(:created_at)
end
def search(query)
where(:id=>Question.select(:quiz_id).where(:name=>/#{query}/i).or(:title=>/#{query}/i)))
end
I think part of the reason you want this is you picked up bad SQL habits
from using ActiveRecord. :)
Thanks,
Jeremy
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