Using UUID instead of ids with Postgres and Rails

Postgres is quite awesome and can do a lot of stuff. For example it can generate UUIDs for you. It also is capable of using these generated UUIDs instead of plain old integer ids.

This is how Rails migrations would look like if want to do something similar:

class EnableUuid < ActiveRecord::Migration
 def up
 execute 'CREATE EXTENSION "uuid-ossp";'
 end

 def down
 execute 'DROP EXTENSION "uuid-ossp";'
 end
end

and then

class CreateEntries < ActiveRecord::Migration
 def up
 execute 'CREATE TABLE entries (id uuid PRIMARY KEY DEFAULT uuid_generate_v4());'
 change_table :entries do |t|
 t.string :name, null: false
 t.timestamps
 end
 end

 def down
 drop_table :entries
 end
end

Written by Pavel Pravosud

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4 Responses

Add your response

dpsk

In Rails 4 uuid is a built-in type for postgres. So it would look like this:

class AddGuuidToSites < ActiveRecord::Migration
 def self.up
 add_column :sites, :guuid, :uuid
 add_index :sites, :guuid
 end

 def self.down
 remove_column :sites, :guuid
 end
end

over 1 year ago ·

rwz

@dpsk you can get the same thing in rails 3 using postgres_ext gem. The main point of this protip is how to make uuid column

primary key
autogenerated

over 1 year ago ·

dpsk

@rwz Sorry, didn't pay attention that you are using uuid as primary key, good stuff :)

over 1 year ago ·

typicalprog

Ugh. Bloat your primary key from an INT to a long string, making indexes much bigger, comparisons take longer. This might make sense if you are sharding and don't have a real primary key, but I can't think of any other reason to do it.

over 1 year ago ·