Chances are at some point you’ve wanted to get the values of a single column from ActiveRecord. You might have done something like this:
user_ids = User.find(:all).map(&:id)
That’s great and all, but hopefully somebody points out that you can pass ActiveRecord#find a :select key.
user_ids = User.find(:all, :select => 'id').map(&:id)
Now we’re getting somewhere. On a “wide” table (ie. one with a lot of columns, large columns, or binary types stored separately) this alone can be a huge improvement, as just sending all that data across the wire can really waste time. While ActiveRecord is generally good enough performance wise, sometimes getting a little closer to the metal is appropriate, and in comes find_ids.
user_ids = User.find_ids
Here’s some benchmarks against a fairly “wide” table with 100 records, 10,000 times for each style:
user system total real find(:all).map 26.460000 3.130000 29.590000 ( 72.656614) find(:all, :select).map 12.770000 0.560000 13.330000 ( 16.232474) find_ids 7.870000 0.340000 8.210000 ( 10.465719)
But that’s not all, it also natively supports other columns, associations, and named scopes.
emails = User.find_column_values('email') User.wristbands.find_ids User.scoped(:order => 'created_at desc').find_ids
script/plugin install git://github.com/stopdropandrew/find_ids.git
It currently only works with MySQL, but submissions for other adapters are welcome.