Check missing indices on foreign keys in your tables

missing_indices.rake

# https://tomafro.net/2009/09/quickly-list-missing-foreign-key-indexes

desc "Check missing indices on foreign keys in your tables"
task missing_indices: :environment do
  c = ActiveRecord::Base.connection
  c.tables.collect do |t|
    columns = c.columns(t).collect(&:name).select {|x| x.ends_with?("_id" || x.ends_with("_type"))}
    indexed_columns = c.indexes(t).collect(&:columns).flatten.uniq
    unindexed = columns - indexed_columns
    unless unindexed.empty?
      puts "#{t}: #{unindexed.join(", ")}"
    end
  end
end