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
_______________________________________________
Rails-core mailing list
Rails-core@lists.rubyonrails.org
http://lists.rubyonrails.org/mailman/listinfo/rails-core
_______________________________________________
Rails-core mailing list
Rails-core@lists.rubyonrails.org
http://lists.rubyonrails.org/mailman/listinfo/rails-core
