On Sep 16, 11:34 pm, surge <[EMAIL PROTECTED]> wrote: > Gotcha. I was thinking about playing with the :select option. That was > my next step before I posted, but I decided to run it by the community > first. :select is nice but you lose the convenience of the Rails > automation, don't you? You can also forget to select an id column for > example. Every new item would require a modification of the select > clause... An SQL view would work but I'm still working with mysql > 4.1 :) And I kind of want to keep as much as possible within the > application. Feels right that way. Let me know if you think I'm > missing something. > > Thank you for your response all the same...
You were partially correct about the relational listing concept. Rails 2.1's eager loading will use 2 SQL statements when you add the :include => :issues option: 1 for the tickets table, and 1 for the issues matching those tickets (in the form of a WHERE IN clause). It's up to AR to compose those records to AR objects with 1-to-many associations. If you have a :condition which specifies something like :condition => "issues.active = 1" You get the scenario which you stated: a cartesian product of the resultset. If you have 100 tickets with 100 issues each, you get 100x100 = 10,000 records, which AR has to compose into 100 AR objects with a 1-to-many associations. It doesn't mean that the tickets will be listed 100 times each, it's just that the resultset will return the tickets 100 times each. But still, a cartesian product is not a very good thing from an optimization point of view. If you really need all the fields from the table, you can always use: :select => "*, COUNT(...) AS issue_count" Although there's a caveat with the :select approach: AFAIK, MySQL 4.1 does not support subqueries, so you might be stuck with the :include option afterall. Or you might want to look here: http://railsexpress.de/blog/articles/2005/11/06/the-case-for-piggy-backed-attributes HTH --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
