[Rails] Re: il.add_index question

Colin Law wrote:
> 2009/10/13 steveb56 <steve.burke.56@gmail.com>:
>> add_index(:friendships, [:friend_id1, :friend_id2], :unique => true)
>>
>> I would also like to add an index to take care of the following
>> situation...
>>
>> id1  id2
>> 1    2
>> 2    1   # Error, since it's the same as the first record
>
> Could you setup your code so that for a friendship record id1 is
> always less than id2? If there is no way in the code that id1=2 and
> id2=1 can occur then you do not need to protect against it.

And if you really want to make this bulletproof, you can enforce id1 <
id2 with a check constraint in the DB.

>
> Colin

Best,
--
Marnen Laibow-Koser
http://www.marnen.org
marnen@marnen.org
--
Posted via http://www.ruby-forum.com/.

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