postgresql autoincrement in migration

Hi    I have a migration to be created with id start from say 100 for example.That is not from 1 So I tried like

create_table :problems, :options => "auto_increment = 100" do |t|     t.column :title, :text

Hi    I have a migration to be created with id start from say 100 for example.That is not from 1 So I tried like

create_table :problems, :options => "auto_increment = 100" do |t|     t.column :title, :text      ------ end

     I am using postgres .But the above auto_increment is mysql syntax i think(Am I right?).And is not working also.How can I change that to get the result?Please help

Hi     Thanks for the reply Sijo