When adding an index on multiple columsn in rails, two indexes are created. How do i prevent that?-CodePudding

So I am currently assigned a task in Ruby which I have never used before and I've run into a very strange problem. I have this migration for a model message, which has an index on chat_id and number.

class CreateMessages < ActiveRecord::Migration[5.2]
  def change
    create_table :messages do |t|
      t.references :chat, foreign_key: true, null: false
      t.integer :number, null: false
      t.string :body
      #t.index [:chat_id, :number] doesn't work
      t.timestamps
    end
    #add_index :messages, [:chat_id, :number] #doesn't work either

  end
end

The end schema of both those migrations when running rails db:migrate is this

create_table "messages", force: :cascade do |t|
    t.integer "chat_id", null: false
    t.integer "number", null: false
    t.string "body"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
    t.index ["chat_id", "number"], name: "index_messages_on_chat_id_and_number"
    t.index ["chat_id"], name: "index_messages_on_chat_id"
  end

Obviously, the second created index is completely useless. How do I prevent this from occuring and create only one index when migrating?

Ruby 2.7.6 Rails 5.2.8.1

CodePudding user response：

This line is adding the index you wish to remove. It accepts an index parameter which defaults to true, change it to:

t.references :chat, foreign_key: true, null: false, index: false