On 2/18/06, Dae San Hwang <[EMAIL PROTECTED]> wrote: > Thank you for the reply! > > I especially liked your analogy of ID to memory address though I'm > not yet 100% convinced. Following are my reasonings behind the > preference for multiple integer column id's: > > 1. I tend to think URL as a part of the user interface. If the user > look at (usually simple and structured in rails application) URL, > wouldn't she be confused by the seemingly random and very large > number assigned to her reply post? Topic's id #87 corresponds to the > 87th-ness nature of the topic posted in the forum. Reply id #3 would > correspond to the 3rd-ness nature of the reply to the given topic, > reply id #1074 would not. I know, I know, I might sound like someone > who is suffering ocd.. ;) > > 2. This one is a bit more practical issue. Let's say I'm building a > public forum hosting service. (It is indeed something I have in > mind.) At some point, my site hosts 10,000 forums, each having its > own forum_id. Let's say each forum has average of 10,000 topics, > each having its own topic_id. And each topic has average of 100 > replies, each having its own reply_id. If I have to use a flat > integer id space, there will be replies with id like #10,000,000,000. > (10,000 * 10,000 * 100) Now, 32-bit unsigned integer can't handle it > since its max value would 4,294,967,295. I could just use 64-bit > unsigned integer, I guess, but it does take more spaces and what if > my site becomes even more successful to the extent even 64-bit > integer will max out? > > In some ways, id's are like memory addresses, but no user ever get to > see the memory address values.. Are there other reasons against the > use of multiple integer column id's other than the fact that > ActiveRecord doesn't support it? > > Thanks, > > daesan > > > On Feb 19, 2006, at 2:57 AM, Michael Koziarski wrote: > > > On 2/18/06, Dae San Hwang <[EMAIL PROTECTED]> wrote: > >> Hi, > >> > >> As I understand, composite primary keys aren't supported in > >> ActiveRecord yet. May I ask if there are plans for this feature? > >> Better yet, if this feature is under development, how's the progress > >> going? > > > > There is currently no work underway to support composite keys with > > active record. At least in rails itself. There might well be some > > plugins under development. > > > >> I'm not trying to use legacy databases. > > > > Then stick with surrogate ids > > > >> I tend to think that using > >> multiple integer column id's (composite primary key) are often > >> natural way to implement one-to-many relationships, for things like > >> "forum replies". For example, ID for the third comment of forum > >> topic #87 should be (87, 3) not (87, 1074), format being (topic_id, > >> reply_id). > > > > You shouldn't be thinking about the IDs, they're only there for the > > sake of persistance, consider them the logical equivalent of an > > address in memory. It doesn't matter what the number is, just that > > there *is* a number. > > > > > > > > > > -- > > Cheers > > > > Koz
map.connect 'topic/:topic/:reply' /topic/87/3 @reply = Reply.find_by_topic_id_and_id(params[:topic], params[:reply]) -- Rick Olson http://techno-weenie.net _______________________________________________ Rails-core mailing list Rails-core@lists.rubyonrails.org http://lists.rubyonrails.org/mailman/listinfo/rails-core
