Non Numeric IDs

Rails
1

So, I’ve seen several references to Rails’ preference for numeric
IDs, and a couple places suggesting that not having them will cause
problems. I have legacy (and frankly prefer) random alphanum strings.
Ultimately isn’t the primary key just seen as a string anyway? So far
I don’t see the big deal. “So far.” So, other than the snickers of
David, what problems am I going to run into by having random string
keys?

– gw (www.railsdev.ws)

2

Hi there. In my experience, you’ll run into a couple of issues:

  1. How do you guarantee the string is unique? I’m guessing that you
    need to create a random string, validate that it is not already
    existent in the database, then recreate it until you find a unique
    key. This is slower than numeric auto incrementing keys

  2. Storage of numeric keys is faster and smaller than alphanumerics

  3. Rails is built around numeric primary keys. This might not matter
    in your case since you are using a legacy database, but with a new
    pure Rails db, its better to follow the conventions.

Chris

3

Chris, thanks for taking a stab, but I’m still looking for a more
detailed cause->effect.

On Nov 13, 2007, at 6:51 AM, Chris E. wrote:

Hi there. In my experience, you’ll run into a couple of issues:

  1. How do you guarantee the string is unique? I’m guessing that you
    need to create a random string, validate that it is not already
    existent in the database, then recreate it until you find a unique
    key. This is slower than numeric auto incrementing keys

  2. Storage of numeric keys is faster and smaller than alphanumerics

I’ve worked with alphanum keys for many years across many apps, so
I’ve been through all the above types of debates. These are reasons
why some people prefer numerics, but they’re not reasons why
alphanumerics won’t work in Rails.

  1. Rails is built around numeric primary keys. This might not matter
    in your case since you are using a legacy database, but with a new
    pure Rails db, its better to follow the conventions.

Not trying to be a dweeb, but this is the type of statement I keep
seeing. There’s no technical facts in there which identifies the
conditions under which a non-numeric key will cause Rails to cough up
a lung.

Convention is one thing, but where will Rails actually break if it is
not followed?

On Nov 13, 2007 9:42 AM, Greg W. [email protected] wrote:

So, I’ve seen several references to Rails’ preference for numeric
IDs, and a couple places suggesting that not having them will cause
problems. I have legacy (and frankly prefer) random alphanum strings.
Ultimately isn’t the primary key just seen as a string anyway? So far
I don’t see the big deal. “So far.” So, other than the snickers of
David, what problems am I going to run into by having random string
keys?

– gw (www.railsdev.ws)

4

On 11/13/07, Greg W. [email protected] wrote:

a lung.

Convention is one thing, but where will Rails actually break if it is
not followed?

I believe that’s just it - no effort has been spent testing Rails w/
non-integer primary keys since Rails doesn’t use them (opinionated
software,
and all that), so nobody will be able to give you a definitive answer as
to
where it will break. You want random alphanumerics? Go for it. It
breaks
and you get to keep both pieces =) (seriously, though, if it breaks,
I’d
submit patches – unless it’s a big departure, I’d expect them to get
rolled
in).

-b

5

On Nov 13, 2007, at 12:22 PM, Jodi S. wrote:
On Nov 13, 2007 9:42 AM, Greg W. [email protected] wrote:

Try in the console

Model.find(“#{my_numeric_id}”) # works
Model.find(“#{my_numeric_id}ANY_STRING”) # works, and returns the
same instance as above

lesson: the finders (not sure about all), strip off non-numeric
characters from the end of the ID field

which would be a really good reason why non-numeric PK’s will bail.

I’m not getting same results as you. Seems that no matter how I slice
up the ID part, I get the record I expect.

I created records 99, 99abc, 99xyz, 99_abc.

Using these tests:

modelID = “99”; PrivilegedUser.find(modelID).userFirstName
modelID = “99abc”; PrivilegedUser.find(modelID).userFirstName
modelID = “99xyz”; PrivilegedUser.find(modelID).userFirstName
modelID = “99_abc”; PrivilegedUser.find(modelID).userFirstName

modelID = “99”; PrivilegedUser.find(“#{modelID}”).userFirstName
modelID = “99abc”; PrivilegedUser.find(“#{modelID}”).userFirstName
modelID = “99xyz”; PrivilegedUser.find(“#{modelID}”).userFirstName
modelID = “99_abc”; PrivilegedUser.find(“#{modelID}”).userFirstName

modelID = “99”; PrivilegedUser.find(“#{modelID}abc”).userFirstName
modelID = “99”; PrivilegedUser.find(“#{modelID}xyz”).userFirstName
modelID = “99”; PrivilegedUser.find(“#{modelID}_abc”).userFirstName

It all works fine for me.

– gw (www.railsdev.ws)

6

Greg -

On 13-Nov-07, at 3:10 PM, Greg W. wrote:

need to create a random string, validate that it is not already

Convention is one thing, but where will Rails actually break if it is

far
I don’t see the big deal. “So far.” So, other than the snickers of
David, what problems am I going to run into by having random string
keys?

– gw (www.railsdev.ws)

Try in the console

Model.find("#{my_numeric_id}") # works
Model.find("#{my_numeric_id}ANY_STRING") # works, and returns the
same instance as above

lesson: the finders (not sure about all), strip off non-numeric
characters from the end of the ID field

which would be a really good reason why non-numeric PK’s will bail.

Jodi