以下のテーブルでパフォーマンスの問題が発生し、ut8mb4の文字エンコードがあり、次のエラーが発生するため、テーブルに複合インデックスを作成しようとしています。
Mysql2::Error: Specified key was too long
エラー全体を以下に示します。-
== 20161103114941 AddIndexOnKeyAndIdOnInvitees: migrating - Shard: master =====
-- add_index(:invitees, [:key, :created_at])
rake aborted!
StandardError: An error has occurred, all later migrations canceled:
Mysql2::Error: Specified key was too long; max key length is 767 bytes: CREATE INDEX `index_invitees_on_key_and_created_at` ON `invitees` (`key`, `created_at`)
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/activerecord-4.2.1/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:299:in `query'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/activerecord-4.2.1/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:299:in `block in execute'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/activerecord-4.2.1/lib/active_record/connection_adapters/abstract_adapter.rb:473:in `block in log'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/activesupport-4.2.1/lib/active_support/notifications/instrumenter.rb:20:in `instrument'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/ar-octopus-0.8.6/lib/octopus/abstract_adapter.rb:15:in `instrument'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/activerecord-4.2.1/lib/active_record/connection_adapters/abstract_adapter.rb:467:in `log'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/activerecord-4.2.1/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:299:in `execute'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/activerecord-4.2.1/lib/active_record/connection_adapters/mysql2_adapter.rb:231:in `execute'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/activerecord-4.2.1/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:529:in `add_index'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/activerecord-4.2.1/lib/active_record/migration.rb:662:in `block in method_missing'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/activerecord-4.2.1/lib/active_record/migration.rb:632:in `block in say_with_time'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/activerecord-4.2.1/lib/active_record/migration.rb:632:in `say_with_time'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/activerecord-4.2.1/lib/active_record/migration.rb:652:in `method_missing'
/var/www/production_hobnob_copy/db/migrate/20161103114941_add_index_on_key_and_id_on_invitees.rb:3:in `change'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/activerecord-4.2.1/lib/active_record/migration.rb:606:in `exec_migration'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/activerecord-4.2.1/lib/active_record/migration.rb:590:in `block (2 levels) in migrate'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/activerecord-4.2.1/lib/active_record/migration.rb:589:in `block in migrate'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/activerecord-4.2.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:292:in `with_connection'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/activerecord-4.2.1/lib/active_record/migration.rb:588:in `migrate'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/activerecord-4.2.1/lib/active_record/migration.rb:765:in `migrate'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/activerecord-4.2.1/lib/active_record/migration.rb:995:in `block in execute_migration_in_transaction'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/activerecord-4.2.1/lib/active_record/migration.rb:1043:in `ddl_transaction'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/activerecord-4.2.1/lib/active_record/migration.rb:994:in `execute_migration_in_transaction'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/activerecord-4.2.1/lib/active_record/migration.rb:956:in `block in migrate'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/activerecord-4.2.1/lib/active_record/migration.rb:952:in `each'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/activerecord-4.2.1/lib/active_record/migration.rb:952:in `migrate'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/ar-octopus-0.8.6/lib/octopus/migration.rb:86:in `migrate_with_octopus'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/activerecord-4.2.1/lib/active_record/migration.rb:820:in `up'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/ar-octopus-0.8.6/lib/octopus/migration.rb:113:in `block in up_with_octopus'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/ar-octopus-0.8.6/lib/octopus/proxy.rb:246:in `block (2 levels) in run_queries_on_shard'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/ar-octopus-0.8.6/lib/octopus/proxy.rb:509:in `using_shard'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/ar-octopus-0.8.6/lib/octopus/proxy.rb:245:in `block in run_queries_on_shard'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/ar-octopus-0.8.6/lib/octopus/proxy.rb:492:in `keeping_connection_proxy'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/ar-octopus-0.8.6/lib/octopus/proxy.rb:244:in `run_queries_on_shard'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/ar-octopus-0.8.6/lib/octopus/proxy.rb:253:in `block in send_queries_to_multiple_shards'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/ar-octopus-0.8.6/lib/octopus/proxy.rb:252:in `map'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/ar-octopus-0.8.6/lib/octopus/proxy.rb:252:in `send_queries_to_multiple_shards'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/ar-octopus-0.8.6/lib/octopus/migration.rb:112:in `up_with_octopus'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/activerecord-4.2.1/lib/active_record/migration.rb:798:in `migrate'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/ar-octopus-0.8.6/lib/octopus/migration.rb:104:in `block in migrate_with_octopus'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/ar-octopus-0.8.6/lib/octopus/proxy.rb:246:in `block (2 levels) in run_queries_on_shard'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/ar-octopus-0.8.6/lib/octopus/proxy.rb:509:in `using_shard'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/ar-octopus-0.8.6/lib/octopus/proxy.rb:245:in `block in run_queries_on_shard'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/ar-octopus-0.8.6/lib/octopus/proxy.rb:492:in `keeping_connection_proxy'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/ar-octopus-0.8.6/lib/octopus/proxy.rb:244:in `run_queries_on_shard'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/ar-octopus-0.8.6/lib/octopus/proxy.rb:253:in `block in send_queries_to_multiple_shards'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/ar-octopus-0.8.6/lib/octopus/proxy.rb:252:in `map'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/ar-octopus-0.8.6/lib/octopus/proxy.rb:252:in `send_queries_to_multiple_shards'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/ar-octopus-0.8.6/lib/octopus/migration.rb:103:in `migrate_with_octopus'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/activerecord-4.2.1/lib/active_record/tasks/database_tasks.rb:137:in `migrate'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/gems/activerecord-4.2.1/lib/active_record/railties/databases.rake:44:in `block (2 levels) in <top (required)>'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/bin/ruby_executable_hooks:15:in `eval'
/home/ubuntu/.rvm/gems/ruby-2.0.0-p648/bin/ruby_executable_hooks:15:in `<main>'
Tasks: TOP => db:migrate
私はこのフォーラムで次の投稿を行いました：-
Railsがschema_migrationsを作成しています-Mysql2 :: Error：指定されたキーが長すぎました
与えられた解決策は、文字エンコードをutf8に変換することですが、これは私の場合は不可能です。これに対する回避策はありますか？
どんな提案や助けも非常に役に立ちます。
どうもありがとう
古いバージョンでは、インデックスは767バイトに制限されていました。これはVARCHAR(255) CHARACTER SET utf8人気のある、のための十分な部屋でした。
VARCHAR(255) CHARACTER SET utf8mb4それ以上のものが必要です。新しいバージョンでは制限が引き上げられているため、機能します。
ソリューション：
手順（5.7.7以降では不要）
SET GLOBAL innodb_file_format=Barracuda;
SET GLOBAL innodb_file_per_table=1;
SET GLOBAL innodb_large_prefix=1;
logout & login (to get the global values);
ALTER TABLE tbl ROW_FORMAT=DYNAMIC;
次に、（255）utf8mb4にインデックスを付けることができます。
「キーが長すぎる」は、インデックスを追加できないという点で「パフォーマンス」に間接的に影響するだけです。
この記事はインターネットから収集されたものであり、転載の際にはソースを示してください。
侵害の場合は、連絡してください[email protected]
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