class AddIndexOnSineCommonness < ActiveRecord::Migration
def change
# We only want to send queries like
# SELECT "symbols".*, "sine_symbol_commonnesses".*
# FROM "symbols" LEFT OUTER JOIN "sine_symbol_commonnesses" ON "sine_symbol_commonnesses"."symbol_id" = "symbols"."id"
# ORDER BY sine_symbol_commonnesses.commonness ASC LIMIT 1
# Thus, we also add an index on the commonness.
add_index :sine_symbol_commonnesses, :commonness
end
end