複合インデックスと重複する単独インデックスを削除 #9915

[JoeJoeflyn]

Issue

• 複合インデックスと重複する単独インデックスの整理 #9915

概要

複合インデックスの先頭カラムと重複する単独インデックスを11件削除しました。PostgreSQLのB-treeインデックスでは複合インデックスの先頭カラム単体での検索にも利用されるため、単独インデックスは冗長です。

削除対象

テーブル	削除したインデックス	代替となる複合インデックス
answers	index_answers_on_question_id	index_answers_on_question_id_and_type
checks	index_checks_on_user_id	index_checks_on_user_id_and_checkable_id_and_checkable_type
coding_test_submissions	index_coding_test_submissions_on_coding_test_id	index_coding_test_submissions_on_coding_test_id_and_user_id
followings	index_followings_on_follower_id	index_followings_on_follower_id_and_followed_id
footprints	index_footprints_on_user_id	index_footprintable
pair_work_schedules	index_pair_work_schedules_on_pair_work_id	index_pair_work_schedules_on_pair_work_id_and_proposed_at
participations	index_participations_on_user_id	index_participations_on_user_id_and_event_id
products	index_products_on_user_id	index_products_on_user_id_and_practice_id
regular_event_participations	index_regular_event_participations_on_user_id	index_user_id_and_regular_event_id
survey_answers	index_survey_answers_on_survey_id	index_survey_answers_on_survey_id_and_user_id
works	index_works_on_user_id	index_works_on_user_id_and_title

変更確認方法

1. chore/remove-redundant-indexes-#9915 をローカルに取り込む
2. bin/rails db:migrate を実行し、エラーなく完了することを確認する
3. bin/rails db:schema:load でスキーマが正しく構築されることを確認する
4. bin/rails test が全てパスすることを確認する

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Configuration used: Path: .coderabbit.yaml

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Run ID: 36740d87-cd62-4f7b-8eea-668886cb9920

📥 Commits

Reviewing files that changed from the base of the PR and between 26efdec and f88e7a9.

📒 Files selected for processing (10)

• db/migrate/20260728000001_remove_index_question_id_from_answers.rb
• db/migrate/20260728000002_remove_index_user_id_from_checks.rb
• db/migrate/20260728000003_remove_index_coding_test_id_from_coding_test_submissions.rb
• db/migrate/20260728000004_remove_index_follower_id_from_followings.rb
• db/migrate/20260728000005_remove_index_user_id_from_footprints.rb
• db/migrate/20260728000006_remove_index_pair_work_id_from_pair_work_schedules.rb
• db/migrate/20260728000007_remove_index_user_id_from_participations.rb
• db/migrate/20260728000008_remove_index_user_id_from_products.rb
• db/migrate/20260728000009_remove_index_user_id_from_regular_event_participations.rb
• db/schema.rb

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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