activerecord-importを利用して無効なデータを無理やりINSERTする

activerecord-importと:on_duplicate_key_ignoreオプションを組み合わせるとカラム定義の範囲外の値であっても無理やりINSERTすることができます。

# frozen_string_literal: true

require "bundler/inline"

gemfile(true) do
  source "https://rubygems.org"

  git_source(:github) { |repo| "https://github.com/#{repo}.git" }

  gem "activerecord", "6.1.0"
  gem "activerecord-import"
  gem "mysql2"
end

require "active_record"
require "logger"

ActiveRecord::Base.establish_connection(adapter: "mysql2", database: "test", username: "root")
ActiveRecord::Base.logger = Logger.new(STDOUT)

ActiveRecord::Schema.define do
  create_table :users, force: true do |t|
    t.string :name, index: { unique: true }
    t.decimal :money, precision: 10
  end
end

class User < ActiveRecord::Base
end

attributes = [
  { name: "foo", money: "10000000000" },
  { name: "foo", money: "20000000000" },
]

User.import(attributes, on_duplicate_key_ignore: true)

# User.insert_all(attributes)

puts
puts User.pluck(:money) # => 9999999999
puts

% ruby foo.rb
Fetching gem metadata from https://rubygems.org/..............
Fetching gem metadata from https://rubygems.org/.
Resolving dependencies...
Using concurrent-ruby 1.1.7
Using bundler 2.2.3
Using minitest 5.14.3
Using zeitwerk 2.4.2
Using mysql2 0.5.3
Using i18n 1.8.7
Using tzinfo 2.0.4
Using activesupport 6.1.0
Using activemodel 6.1.0
Using activerecord 6.1.0
Using activerecord-import 1.0.7
-- create_table(:users, {:force=>true})
D, [2021-01-06T14:04:10.296375 #81282] DEBUG -- :    (66.5ms)  DROP TABLE IF EXISTS `users`
D, [2021-01-06T14:04:10.377990 #81282] DEBUG -- :    (80.7ms)  CREATE TABLE `users` (`id` bigint NOT NULL AUTO_INCREMENT PRIMARY KEY, `name` varchar(255), `money` decimal(10), UNIQUE INDEX `index_users_on_name` (`name`))
   -> 0.1967s
D, [2021-01-06T14:04:10.397652 #81282] DEBUG -- :   ActiveRecord::InternalMetadata Load (0.5ms)  SELECT `ar_internal_metadata`.* FROM `ar_internal_metadata` WHERE `ar_internal_metadata`.`key` = 'environment' LIMIT 1
D, [2021-01-06T14:04:10.417055 #81282] DEBUG -- :    (0.3ms)  SELECT @@max_allowed_packet
D, [2021-01-06T14:04:10.424171 #81282] DEBUG -- :   User Create Many (6.8ms)  INSERT IGNORE INTO `users` (`name`,`money`) VALUES ('foo',10000000000),('foo',20000000000)

D, [2021-01-06T14:04:10.428391 #81282] DEBUG -- :    (3.4ms)  SELECT `users`.`money` FROM `users`
9999999999

https://gist.github.com/kamipo/3db82c3bb7cbcbf007b4d4367a5c5227

これはどういう原理かというと、activerecord-importではINSERTしたいけどすでに(ユニークキーが)おなじレコードがあるときはスルーしたい(i.e. on_duplicate_key_ignore)という機能を実現するのにMySQLではINSERT IGNORE構文を使っていて、INSERT IGNOREではINSERT中のすべてのエラーを無視して無効な値は可能ならもっとも近い値に調整してINSERTするという振る舞いをするため、このような挙動を引き起こすことができます。

では、INSERTしたいけどすでに(ユニークキーが)おなじレコードがあるときはスルーしたい、けど無効な値はちゃんとエラーにしてほしいときはどうしたらいいかというと、Rails 6.0から使えるinsert_allというバルクインサート用のAPIを使うことができます。RailsチームではわいがMySQLチョットデキルので、この問題についてはレビューでフィードバックして対処されており安心してご利用になることができます。

github.com

See also

songmu.jp

それでは本年も引き続きよろしくおねがいいたします。

create_or_find_byでcreateもfind_byも失敗させる

Active Recordの話です。

create_or_find_byの実装はcreateしてみてユニーク制約に引っかかったらfind_byしてみるなので、ふつうに考えるとfind_byは成功しそうに見えます。

    def create_or_find_by(attributes, &block)
      transaction(requires_new: true) { create(attributes, &block) }
    rescue ActiveRecord::RecordNotUnique
      find_by!(attributes)
    end

ですが、以下のスクリプトを実行するとcreate_or_find_byはcreateがRecordNotUnique例外を吐いたあと、find_byもRecordNotFound例外を吐いてレコードを見つけられずに死にます。

ちょっと今から会食なので原理は帰ってから書き足しますしばしお待ちを🙇‍♂️

これ時間あったら続き書きたいけどとりいそぎ説明すると、REPEATABLE READでファントムリードを防いでることを利用して失敗させてるからREAD COMMITTEDにしてファントムリードを許すかSERIALIZABLEにするかLocking Readして別トランザクションの更新をブロックすると失敗を防げます。 https://t.co/v4LBhwDWeR

— Ryuta Kamizono (@kamipo) December 20, 2020

https://github.com/rails/rails/blob/3e5d504f7828118928bfcc08e5be284775836794/activerecord/lib/active_record/relation.rb#L208-L212

# frozen_string_literal: true

require "bundler/inline"

gemfile(true) do
  source "https://rubygems.org"

  git_source(:github) { |repo| "https://github.com/#{repo}.git" }

  gem "activerecord", "6.1.0"
  gem "mysql2"
end

require "active_record"
require "logger"

ActiveRecord::Base.establish_connection(adapter: "mysql2", database: "test", username: "root")
ActiveRecord::Base.logger = Logger.new(STDOUT)

ActiveRecord::Schema.define do
  create_table :users, force: true do |t|
    t.string :name, index: { unique: true }
  end
end

class User < ActiveRecord::Base
end

t = Thread.new do
  sleep 0.1
  User.create!(name: "foo")
end

User.transaction do
  User.find_by!(name: "foo")
rescue ActiveRecord::RecordNotFound
  puts 'User<name: "foo"> not found'

  sleep 0.2

  User.create_or_find_by!(name: "foo").tap do
    puts 'User<name: "foo"> has found or created'
  end
end

t.join

% ruby foo.rb
Fetching gem metadata from https://rubygems.org/.........
Resolving dependencies...
Using concurrent-ruby 1.1.7
Using i18n 1.8.5
Using minitest 5.14.2
Using tzinfo 2.0.3
Using zeitwerk 2.4.2
Using activesupport 6.1.0
Using activemodel 6.1.0
Using activerecord 6.1.0
Using bundler 2.1.4
Using mysql2 0.5.3
-- create_table(:users, {:force=>true})
D, [2020-12-16T18:55:22.915787 #49715] DEBUG -- :    (12.2ms)  DROP TABLE IF EXISTS `users`
D, [2020-12-16T18:55:22.954341 #49715] DEBUG -- :    (37.5ms)  CREATE TABLE `users` (`id` bigint NOT NULL AUTO_INCREMENT PRIMARY KEY, `name` varchar(255), UNIQUE INDEX `index_users_on_name` (`name`))
   -> 0.0754s
D, [2020-12-16T18:55:23.132151 #49715] DEBUG -- :   ActiveRecord::InternalMetadata Load (0.7ms)  SELECT `ar_internal_metadata`.* FROM `ar_internal_metadata` WHERE `ar_internal_metadata`.`key` = 'environment' LIMIT 1
D, [2020-12-16T18:55:23.147310 #49715] DEBUG -- :   TRANSACTION (0.3ms)  BEGIN
D, [2020-12-16T18:55:23.151778 #49715] DEBUG -- :   User Load (0.8ms)  SELECT `users`.* FROM `users` WHERE `users`.`name` = 'foo' LIMIT 1
User<name: "foo"> not found
D, [2020-12-16T18:55:23.283424 #49715] DEBUG -- :   TRANSACTION (0.3ms)  BEGIN
D, [2020-12-16T18:55:23.287159 #49715] DEBUG -- :   User Create (3.5ms)  INSERT INTO `users` (`name`) VALUES ('foo')
D, [2020-12-16T18:55:23.290553 #49715] DEBUG -- :   TRANSACTION (2.8ms)  COMMIT
D, [2020-12-16T18:55:23.359126 #49715] DEBUG -- :   TRANSACTION (0.3ms)  SAVEPOINT active_record_1
D, [2020-12-16T18:55:23.360585 #49715] DEBUG -- :   User Create (1.2ms)  INSERT INTO `users` (`name`) VALUES ('foo')
D, [2020-12-16T18:55:23.361383 #49715] DEBUG -- :   TRANSACTION (0.3ms)  ROLLBACK TO SAVEPOINT active_record_1
D, [2020-12-16T18:55:23.362859 #49715] DEBUG -- :   User Load (0.5ms)  SELECT `users`.* FROM `users` WHERE `users`.`name` = 'foo' LIMIT 1
D, [2020-12-16T18:55:23.363994 #49715] DEBUG -- :   TRANSACTION (0.5ms)  ROLLBACK
Traceback (most recent call last):
    12: from foo.rb:34:in `<main>'
    11: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/transactions.rb:209:in `transaction'
    10: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract/database_statements.rb:320:in `transaction'
     9: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract/transaction.rb:308:in `within_new_transaction'
     8: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `synchronize'
     7: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `handle_interrupt'
     6: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `block in synchronize'
     5: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `handle_interrupt'
     4: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:26:in `block (2 levels) in synchronize'
     3: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract/transaction.rb:310:in `block in within_new_transaction'
     2: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract/database_statements.rb:320:in `block in transaction'
     1: from foo.rb:35:in `block in <main>'
/Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/core.rb:366:in `find_by!': Couldn't find User (ActiveRecord::RecordNotFound)
    87: from foo.rb:34:in `<main>'
    86: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/transactions.rb:209:in `transaction'
    85: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract/database_statements.rb:320:in `transaction'
    84: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract/transaction.rb:308:in `within_new_transaction'
    83: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `synchronize'
    82: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `handle_interrupt'
    81: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `block in synchronize'
    80: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `handle_interrupt'
    79: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:26:in `block (2 levels) in synchronize'
    78: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract/transaction.rb:310:in `block in within_new_transaction'
    77: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract/database_statements.rb:320:in `block in transaction'
    76: from foo.rb:35:in `block in <main>'
    75: from foo.rb:41:in `rescue in block in <main>'
    74: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/querying.rb:22:in `create_or_find_by!'
    73: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/relation.rb:218:in `create_or_find_by!'
    72: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/relation/delegation.rb:108:in `method_missing'
    71: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/relation.rb:406:in `scoping'
    70: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/relation.rb:811:in `_scoping'
    69: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/relation.rb:406:in `block in scoping'
    68: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/relation/delegation.rb:108:in `block in method_missing'
    67: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/relation/delegation.rb:108:in `public_send'
    66: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/transactions.rb:209:in `transaction'
    65: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract/database_statements.rb:320:in `transaction'
    64: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract/transaction.rb:308:in `within_new_transaction'
    63: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `synchronize'
    62: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `handle_interrupt'
    61: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `block in synchronize'
    60: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `handle_interrupt'
    59: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:26:in `block (2 levels) in synchronize'
    58: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract/transaction.rb:310:in `block in within_new_transaction'
    57: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract/database_statements.rb:320:in `block in transaction'
    56: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/relation.rb:218:in `block in create_or_find_by!'
    55: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/relation.rb:114:in `create!'
    54: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/relation.rb:406:in `scoping'
    53: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/relation.rb:811:in `_scoping'
    52: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/relation.rb:406:in `block in scoping'
    51: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/relation.rb:114:in `block in create!'
    50: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/relation.rb:806:in `_create!'
    49: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/persistence.rb:55:in `create!'
    48: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/suppressor.rb:48:in `save!'
    47: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/transactions.rb:300:in `save!'
    46: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/transactions.rb:348:in `with_transaction_returning_status'
    45: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract/database_statements.rb:318:in `transaction'
    44: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/transactions.rb:352:in `block in with_transaction_returning_status'
    43: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/transactions.rb:300:in `block in save!'
    42: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/validations.rb:53:in `save!'
    41: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/persistence.rb:507:in `save!'
    40: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/timestamp.rb:126:in `create_or_update'
    39: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/callbacks.rb:457:in `create_or_update'
    38: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/callbacks.rb:824:in `_run_save_callbacks'
    37: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/callbacks.rb:98:in `run_callbacks'
    36: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/callbacks.rb:457:in `block in create_or_update'
    35: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/persistence.rb:900:in `create_or_update'
    34: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/timestamp.rb:108:in `_create_record'
    33: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/callbacks.rb:461:in `_create_record'
    32: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/callbacks.rb:824:in `_run_create_callbacks'
    31: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/callbacks.rb:98:in `run_callbacks'
    30: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/callbacks.rb:461:in `block in _create_record'
    29: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/attribute_methods/dirty.rb:201:in `_create_record'
    28: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/locking/optimistic.rb:79:in `_create_record'
    27: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/counter_cache.rb:166:in `_create_record'
    26: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/persistence.rb:929:in `_create_record'
    25: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/persistence.rb:375:in `_insert_record'
    24: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract/query_cache.rb:22:in `insert'
    23: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract/database_statements.rb:171:in `insert'
    22: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract/database_statements.rb:136:in `exec_insert'
    21: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/mysql/database_statements.rb:55:in `exec_query'
    20: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:215:in `execute_and_free'
    19: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/mysql/database_statements.rb:50:in `execute'
    18: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:204:in `execute'
    17: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract_adapter.rb:688:in `log'
    16: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/notifications/instrumenter.rb:24:in `instrument'
    15: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract_adapter.rb:696:in `block in log'
    14: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `synchronize'
    13: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `handle_interrupt'
    12: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `block in synchronize'
    11: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `handle_interrupt'
    10: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:26:in `block (2 levels) in synchronize'
     9: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract_adapter.rb:697:in `block (2 levels) in log'
     8: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:205:in `block in execute'
     7: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/dependencies/interlock.rb:47:in `permit_concurrent_loads'
     6: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/share_lock.rb:187:in `yield_shares'
     5: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/dependencies/interlock.rb:48:in `block in permit_concurrent_loads'
     4: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:206:in `block (2 levels) in execute'
     3: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/mysql2-0.5.3/lib/mysql2/client.rb:130:in `query'
     2: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/mysql2-0.5.3/lib/mysql2/client.rb:130:in `handle_interrupt'
     1: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/mysql2-0.5.3/lib/mysql2/client.rb:131:in `block in query'
/Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/mysql2-0.5.3/lib/mysql2/client.rb:131:in `_query': Duplicate entry 'foo' for key 'users.index_users_on_name' (Mysql2::Error)
    87: from foo.rb:34:in `<main>'
    86: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/transactions.rb:209:in `transaction'
    85: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract/database_statements.rb:320:in `transaction'
    84: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract/transaction.rb:308:in `within_new_transaction'
    83: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `synchronize'
    82: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `handle_interrupt'
    81: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `block in synchronize'
    80: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `handle_interrupt'
    79: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:26:in `block (2 levels) in synchronize'
    78: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract/transaction.rb:310:in `block in within_new_transaction'
    77: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract/database_statements.rb:320:in `block in transaction'
    76: from foo.rb:35:in `block in <main>'
    75: from foo.rb:41:in `rescue in block in <main>'
    74: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/querying.rb:22:in `create_or_find_by!'
    73: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/relation.rb:218:in `create_or_find_by!'
    72: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/relation/delegation.rb:108:in `method_missing'
    71: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/relation.rb:406:in `scoping'
    70: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/relation.rb:811:in `_scoping'
    69: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/relation.rb:406:in `block in scoping'
    68: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/relation/delegation.rb:108:in `block in method_missing'
    67: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/relation/delegation.rb:108:in `public_send'
    66: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/transactions.rb:209:in `transaction'
    65: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract/database_statements.rb:320:in `transaction'
    64: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract/transaction.rb:308:in `within_new_transaction'
    63: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `synchronize'
    62: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `handle_interrupt'
    61: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `block in synchronize'
    60: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `handle_interrupt'
    59: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:26:in `block (2 levels) in synchronize'
    58: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract/transaction.rb:310:in `block in within_new_transaction'
    57: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract/database_statements.rb:320:in `block in transaction'
    56: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/relation.rb:218:in `block in create_or_find_by!'
    55: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/relation.rb:114:in `create!'
    54: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/relation.rb:406:in `scoping'
    53: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/relation.rb:811:in `_scoping'
    52: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/relation.rb:406:in `block in scoping'
    51: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/relation.rb:114:in `block in create!'
    50: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/relation.rb:806:in `_create!'
    49: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/persistence.rb:55:in `create!'
    48: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/suppressor.rb:48:in `save!'
    47: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/transactions.rb:300:in `save!'
    46: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/transactions.rb:348:in `with_transaction_returning_status'
    45: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract/database_statements.rb:318:in `transaction'
    44: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/transactions.rb:352:in `block in with_transaction_returning_status'
    43: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/transactions.rb:300:in `block in save!'
    42: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/validations.rb:53:in `save!'
    41: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/persistence.rb:507:in `save!'
    40: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/timestamp.rb:126:in `create_or_update'
    39: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/callbacks.rb:457:in `create_or_update'
    38: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/callbacks.rb:824:in `_run_save_callbacks'
    37: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/callbacks.rb:98:in `run_callbacks'
    36: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/callbacks.rb:457:in `block in create_or_update'
    35: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/persistence.rb:900:in `create_or_update'
    34: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/timestamp.rb:108:in `_create_record'
    33: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/callbacks.rb:461:in `_create_record'
    32: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/callbacks.rb:824:in `_run_create_callbacks'
    31: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/callbacks.rb:98:in `run_callbacks'
    30: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/callbacks.rb:461:in `block in _create_record'
    29: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/attribute_methods/dirty.rb:201:in `_create_record'
    28: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/locking/optimistic.rb:79:in `_create_record'
    27: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/counter_cache.rb:166:in `_create_record'
    26: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/persistence.rb:929:in `_create_record'
    25: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/persistence.rb:375:in `_insert_record'
    24: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract/query_cache.rb:22:in `insert'
    23: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract/database_statements.rb:171:in `insert'
    22: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract/database_statements.rb:136:in `exec_insert'
    21: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/mysql/database_statements.rb:55:in `exec_query'
    20: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:215:in `execute_and_free'
    19: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/mysql/database_statements.rb:50:in `execute'
    18: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:204:in `execute'
    17: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract_adapter.rb:688:in `log'
    16: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/notifications/instrumenter.rb:24:in `instrument'
    15: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract_adapter.rb:696:in `block in log'
    14: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `synchronize'
    13: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `handle_interrupt'
    12: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `block in synchronize'
    11: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `handle_interrupt'
    10: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:26:in `block (2 levels) in synchronize'
     9: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract_adapter.rb:697:in `block (2 levels) in log'
     8: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:205:in `block in execute'
     7: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/dependencies/interlock.rb:47:in `permit_concurrent_loads'
     6: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/share_lock.rb:187:in `yield_shares'
     5: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/dependencies/interlock.rb:48:in `block in permit_concurrent_loads'
     4: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:206:in `block (2 levels) in execute'
     3: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/mysql2-0.5.3/lib/mysql2/client.rb:130:in `query'
     2: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/mysql2-0.5.3/lib/mysql2/client.rb:130:in `handle_interrupt'
     1: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/mysql2-0.5.3/lib/mysql2/client.rb:131:in `block in query'
/Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/mysql2-0.5.3/lib/mysql2/client.rb:131:in `_query': Mysql2::Error: Duplicate entry 'foo' for key 'users.index_users_on_name' (ActiveRecord::RecordNotUnique)
    18: from foo.rb:34:in `<main>'
    17: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/transactions.rb:209:in `transaction'
    16: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract/database_statements.rb:320:in `transaction'
    15: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract/transaction.rb:308:in `within_new_transaction'
    14: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `synchronize'
    13: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `handle_interrupt'
    12: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `block in synchronize'
    11: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `handle_interrupt'
    10: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.0/lib/active_support/concurrency/load_interlock_aware_monitor.rb:26:in `block (2 levels) in synchronize'
     9: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract/transaction.rb:310:in `block in within_new_transaction'
     8: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/connection_adapters/abstract/database_statements.rb:320:in `block in transaction'
     7: from foo.rb:35:in `block in <main>'
     6: from foo.rb:41:in `rescue in block in <main>'
     5: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/querying.rb:22:in `create_or_find_by!'
     4: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/relation.rb:217:in `create_or_find_by!'
     3: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/relation.rb:220:in `rescue in create_or_find_by!'
     2: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/relation/finder_methods.rb:87:in `find_by!'
     1: from /Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/relation/finder_methods.rb:104:in `take!'
/Users/kamipo/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activerecord-6.1.0/lib/active_record/relation/finder_methods.rb:354:in `raise_record_not_found_exception!': Couldn't find User with [WHERE `users`.`name` = ?] (ActiveRecord::RecordNotFound)

https://gist.github.com/kamipo/480f9e6fb61bef0f36b1edbccfd30f66

SELECT ... FOR UPDATE同士でデッドロックさせる

最近SELECT ... FOR UPDATEでデッドロックする話を何度かしたので。

前職のときにUPDATE同士がデッドロックしてたときに、SELECT ... FOR UPDATEで排他ロックを取ってからUPDATEしてデッドロックを防ぎますってPRをレビューしてたときのことで、複数レコードの排他ロックは一瞬ですべてのレコードのロックを取れるわけではなく、ロックを取る順番が揃っていないと簡単にデッドロックしますよという話です。

https://gist.github.com/kamipo/0bb4e37d58ba18a8cefb8aa02f778231

# frozen_string_literal: true

require "mysql2"

def client
  Mysql2::Client.new(
    host: "localhost",
    username: "root",
    database: "test",
  )
end

c1 = client
c2 = client

c1.query("DROP TABLE IF EXISTS `user_tables`")
c1.query <<-SQL
CREATE TABLE `user_tables` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(255) NOT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `index_user_tables_on_name` (`name`)
)
SQL

1000.downto(1) do |i|
  c1.query("INSERT INTO `user_tables` (`name`) VALUES ('p#{i}')")
end

t = Thread.new do
  100.times do |j|
    c2.query("BEGIN")
    #puts "c2 locking:#{j}"
    c2.query("SELECT 1 FROM `user_tables` FORCE INDEX(index_user_tables_on_name) WHERE `name` IN (#{1000.downto(1).map{|i|"'p#{i}'"}.join(",")}) FOR UPDATE")
    #puts "c2 locked:#{j}"
    c2.query("COMMIT")
  end
end

100.times do |j|
  c1.query("BEGIN")
  #puts "c1 locking:#{j}"
  c1.query("SELECT 1 FROM `user_tables` FORCE INDEX(PRIMARY) WHERE `id` IN (#{1.upto(1000).to_a.join(",")}) FOR UPDATE")
  #puts "c1 locked:#{j}"
  c1.query("COMMIT")
end

t.join

% be ruby lock.rb
/Users/kamipo/.rbenv/versions/2.7.0-dev/lib/ruby/gems/2.7.0/gems/bundler-1.17.3/lib/bundler/rubygems_integration.rb:200: warning: constant Gem::ConfigMap is deprecated
/Users/kamipo/.rbenv/versions/2.7.0-dev/lib/ruby/gems/2.7.0/gems/bundler-1.17.3/lib/bundler/rubygems_integration.rb:200: warning: constant Gem::ConfigMap is deprecated
#<Thread:0x00007fa6099b38c0@lock.rb:30 run> terminated with exception (report_on_exception is true):
Traceback (most recent call last):
    6: from lock.rb:31:in `block in <main>'
    5: from lock.rb:31:in `times'
    4: from lock.rb:34:in `block (2 levels) in <main>'
    3: from /Users/kamipo/src/github.com/brianmario/mysql2/lib/mysql2/client.rb:130:in `query'
    2: from /Users/kamipo/src/github.com/brianmario/mysql2/lib/mysql2/client.rb:130:in `handle_interrupt'
    1: from /Users/kamipo/src/github.com/brianmario/mysql2/lib/mysql2/client.rb:138:in `block in query'
/Users/kamipo/src/github.com/brianmario/mysql2/lib/mysql2/client.rb:138:in `_query': Deadlock found when trying to get lock; try restarting transaction (Mysql2::Error)
Traceback (most recent call last):
    6: from lock.rb:31:in `block in <main>'
    5: from lock.rb:31:in `times'
    4: from lock.rb:34:in `block (2 levels) in <main>'
    3: from /Users/kamipo/src/github.com/brianmario/mysql2/lib/mysql2/client.rb:130:in `query'
    2: from /Users/kamipo/src/github.com/brianmario/mysql2/lib/mysql2/client.rb:130:in `handle_interrupt'
    1: from /Users/kamipo/src/github.com/brianmario/mysql2/lib/mysql2/client.rb:138:in `block in query'
/Users/kamipo/src/github.com/brianmario/mysql2/lib/mysql2/client.rb:138:in `_query': Deadlock found when trying to get lock; try restarting transaction (Mysql2::Error)

これはどういう原理でデッドロックさせているかというと、プライマリキーとセカンダリキーで意図的に並び順が異なるようなデータを生成して、プライマリキーを使う実行計画のSELECT ... FOR UPDATEとセカンダリキーを使う実行計画のSELECT ... FOR UPDATEが真逆の順序でレコードのロックを取るように仕向けてデッドロックを引き起こさせています。

このように、複数レコードのロックは一瞬で同時に起きるわけではなく、順番に起きて途中の状態(ロックが取り終わったレコードとこれからロックを取るつもりのレコードがある状態)が存在するので、ロックを取る順番が一意になるようにクエリや実行計画を揃えるというのがこの手の問題に対する一般的な対処法になります。

ロックを取る順番って見えづらいので問題に気づきづらいですよね、かくいう僕も眼の良さを活かして気合いで対処してるので、なんかいい方法あったら教えてください。

ツイッターで見つけて直したActiveRecordの問題さらに3つ

ツイッターで見つけて直したActiveRecordの問題3つ - かみぽわーるの続き。

• where(id: ..1) ("id" <= 1)をnotしたら"id" > 1になってほしい

今のmasterで試してみたのですが、SELECT "users".* FROM "users" WHERE NOT ("users"."id" <= 1) になるようです。 https://t.co/pQh4h9g0MP

— 神速 (@sinsoku_listy) August 3, 2019

github.com

• association先のカラムをpluckしたときもちゃんとtype castされてほしい

対応ありがとうございます！
制限があるとはいえ、定義ではなく呼び出し側で解決を図れるのは嬉しいです。

ちなみに association の情報を与えてあげるようなアプローチは既に検討済みですか？例えばこういう…
User.joins(:association).pluck(association: :column_name)

— _h_s_ (@_h_s_) May 14, 2020

github.com

• rewhereでちゃんとテーブルを考慮してwhere句を上書きしてほしい

rewhere(except) がテーブルを考慮するようになればだいぶ楽になるなあ

— バンビちゃん@実際存在しません (@pink_bangbi) November 29, 2019

ActiveRecord むずかしいにゃんねえ
【Ruby on Rails Advent Calendar 2019】ActiveRecord で後から where クエリを上書きする【2日目】 - Secret Garden(Instrumental) https://t.co/ojNO3TZrBA

— バンビちゃん@実際存在しません (@pink_bangbi) December 1, 2019

github.com

ツイッターで見つけて直したActiveRecordの問題3つ

Rails Advent Calendar 2020の3日目です。

時間がないのでとりいそぎ3つだけ。

• enum state: {active: 0, inactive: 1}とかした時に、typecast前の0とか1を取りたい

ActiveRecord::Enumってstate: {active: 0, inactive: 1}とかした時に、typecast前の0とか1を取る場合、read_attribute_before_type_castを使うしかないのか？

— アルフォートおじさん (@joker1007) October 21, 2020

github.com

• belongs_to :author, class_name: 'User'したときにleft_joins(:author).where("author.id": nil)とか書きたい

これすると、joins(:author).where(users: { id: nil }) みたいに書く必要もあったり、各所でオプションが必要になったりで、個人的にはあまり好きじゃない。

— 神速 (@sinsoku_listy) June 4, 2020

github.com

• attributeでDBの型情報を保ったままdefault値だけ定義したい

ActiveRecordでDBから動的にprecisionを取得しつつ
attribute(..., default: '') でデフォルト値を定義する方法、無いな🙄

誰もそんなことをする人おらんもんな。
どうしたもんかねぇ。

— いっくん (@alpaca_tc) July 7, 2020

github.com

ISUCON10予選ふりかえり

ISUCON10予選おつかれさまでした。ISUUMOいい問題でしたね。過去出題側を担当したこともある身でも、参加者の完全攻略に対する怖れもあって仕様が肥大化するなか今回これだけコンパクトな仕様のアプリケーションでこれだけ楽しめる出題をしたのマジですごいと思いました。

今回の問題はMySQLかつ検索ヘヴィな問題で僕のバックグラウンドに向いてる問題にも関わらず、ずっと手を動かしていたわりに効果の高い施策に取り組めず、あらためてISUCONの難しさを痛感したしこれぞISUCONなのだなあと思います。

僕の文章読解が遅く仕様理解にとても時間を要するという性質から、これまでのISUCONでは常にアプリケーションの仕様や性質を理解できる前に時間的制約からあらゆる決断を迫られるという状況にあり、この状況で仕様や性質を理解できていたとしたらできた正しい決断をしていくのは本当に難しいと思っていて、今回ずっと手を動かしていたわりに結果が振るわなかったのもひとえにその難しさだなあと個人的には思っています。

時間を節約するために個人的にとても時間を要する仕様書を読むのを疎かにして失敗したこともあるし、DBボトルネックが支配的ではない問題でスロークエリの対処に時間を投下してアプリケーション仕様を最後までちゃんと理解しないまま失敗したこともある。僕の技術的なバックグラウンドであるMySQLがボトルネックの支配的な要素ではない近年のISUCONで、チームで唯一普段Rubyを書いている僕が、自分の有限の時間を何に投下するかというのをその場その場で決断していくのはとてもハードだったなと感じた。だけれど、そのことの精度を上げていくことがISUCONでの結果に繋がっていくのではないかというのが今回ISUCON10予選を終えて感じた個人的な総括になります。

今回手元で動かせるアプリケーションでもあったので、今日起きてから予定の合間合間に予選で決断できなかったDB側の感想戦をしてみたけど、いやぁこれがその場でできないのがマジでISUCONだなあとあらためて思った。未来のいつかの自分のために今日のこの気持ちをここにしたためておきます。

DB側感想戦

感想戦: index comment by kamipo · Pull Request #12 · soudai/isucon10-qualify · GitHub

8e98179ad6 以降のスキーマ変更(index削除とか)効いてなかった by kamipo · Pull Request #13 · soudai/isucon10-qualify · GitHub

感想戦: Add descending index `popularity DESC` by kamipo · Pull Request #14 · soudai/isucon10-qualify · GitHub

不要なindex削除 by kamipo · Pull Request #15 · soudai/isucon10-qualify · GitHub

Optimize get '/api/recommended_estate/:id' by kamipo · Pull Request #16 · soudai/isucon10-qualify · GitHub

Optimize post '/api/chair/buy/:id' by kamipo · Pull Request #17 · soudai/isucon10-qualify · GitHub

Avoid N+1 in post '/api/estate/nazotte' by kamipo · Pull Request #18 · soudai/isucon10-qualify · GitHub

Treasure Dataを退職します

急なお知らせですが、8月31日をもってTreasure Dataを退職することになりました。

今後の活動についてはいまのところなにも決まっていないので、自分になにができるのか、どんなニーズがあるのか、いろいろ相談に乗ってもらえるとうれしいです。

きっかけはというと、長年Railsコントリビューター/メンテナーとして並々ならぬ思いで活動してきたんですが。

どのぐらいがんばっていたかというと、たとえば2020年8月時点のコミット数ベースの今年のアクティビティでいうと、上位10人のアクティビティを母数にするとその半数が僕になります。

rails/rails contributors 2020-01-01 - 2020-08-26

Rails 5.0以降のも置いておきます。

rails/rails contributors 2019-01-01 - 2019-12-31
rails/rails contributors 2018-01-01 - 2018-12-31
rails/rails contributors 2017-01-01 - 2017-12-31
rails/rails contributors 2016-01-01 - 2016-12-31

さすがにこんなにがんばっとるねんからこれ仕事ってことにならん？という思いをずっと持っていて、オンライン飲みで友人にそのことを相談したらメンテナーのポジションで選考してもらえて、そこではマッチングには至らなかったんですが、それでなんか吹っ切れたというか。

自分になにができるのか、どんなニーズがあるのか、どんな選択肢があるのか、それを探すのがいま一番やりたいことだなと。

こんな時期なのでなかなか難しいとは思うんですが、いろいろ相談に乗ってもらえたり、あとずっと引きこもってこんな活動を続けていたため知り合いが少ないので、誰かしら繋いでくれたりするとうれしいです。人生の新たな楽しみを見つけたいです。

とりあえず飲みにいきたい。遊びに誘ってくれても全然オッケーです。