ruby-on-rails - 索引名称“index_name”太长；限制为63个字符

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How do I handle too long index names in a Ruby on Rails ActiveRecord migration?
（6个答案）
去年关门了。
当我运行rails迁移命令时。我得到的索引名太长了。
我的迁移文件

class AddMissingIndices < ActiveRecord::Migration
  def change
    # We'll explicitly specify its name, as the auto-generated name is too long and exceeds 63
    # characters limitation.
    add_index :mailboxer_conversation_opt_outs, [:unsubscriber_id, :unsubscriber_type],
      name: 'index_mailboxer_conversation_opt_outs_on_unsubscriber_id_type'
    add_index :mailboxer_conversation_opt_outs, :conversation_id

    add_index :mailboxer_notifications, :type
    add_index :mailboxer_notifications, [:sender_id, :sender_type]

    # We'll explicitly specify its name, as the auto-generated name is too long and exceeds 63
    # characters limitation.
    add_index :mailboxer_notifications, [:notified_object_id, :notified_object_type],
      name: 'index_mailboxer_notifications_on_notified_object_id_and_type'

    add_index :mailboxer_receipts, [:receiver_id, :receiver_type]
  end
end

服务器日志是
rails中止！
标准错误：发生错误，此迁移和所有以后的迁移都被取消：
索引名称“Index_mailboxer_conversation_opt_outs_on_unsubscriber_type_and_unsubscriber_id”表“mailboxer_conversation_opt_outs”太长；限制为63个字符
/home/sharat/.rvm/gems/ruby-2.4.3/gems/active record-5.2.0/lib/active_record/connection_adapters/abstract/schema_语句
/home/sharat/.rvm/gems/ruby-2.4.3/gems/active record-5.2.0/lib/active_record/connection_adapters/postgresql/schema_语句。rb:465:在create_table中的validate_index_length!' /home/sharat/.rvm/gems/ruby-2.4.3/gems/activerecord-5.2.0/lib/active_record/connection_adapters/abstract/schema_statements.rb:1166:in块中
/home/sharat/.rvm/gems/ruby-2.4.3/gems/active record-5.2.0/lib/active_record/connection_adapters/abstract/schema_语句
/home/sharat/.rvm/gems/ruby-2.4.3/gems/active record-5.2.0/lib/active_record/migration.rb:871:inadd_index' /home/sharat/.rvm/gems/ruby-2.4.3/gems/activerecord-5.2.0/lib/active_record/connection_adapters/abstract/schema_statements.rb:315:in用时间阻塞say_
/home/sharat/.rvm/gems/ruby-2.4.3/gems/active record-5.2.0/lib/active_record/migration.rb:840:ineach' /home/sharat/.rvm/gems/ruby-2.4.3/gems/activerecord-5.2.0/lib/active_record/connection_adapters/abstract/schema_statements.rb:314:inmethod_missing'
/home/sharat/.rvm/gems/ruby-2.4.3/gems/active record-5.2.0/lib/active_record/migration/compatibility.rb:36:inblock in method_missing' /home/sharat/.rvm/gems/ruby-2.4.3/gems/activerecord-5.2.0/lib/active_record/migration.rb:840:increate_table'
/主页/sharat/.rvm/gems/ruby-2.4.3/gems/active record-5.2.0/lib/active_record/migration.rb:604:insay_with_time' /home/sharat/.rvm/gems/ruby-2.4.3/gems/activerecord-5.2.0/lib/active_record/migration.rb:860:inup'
/home/sharat/.rvm/gems/ruby-2.4.3/gems/active record-5.2.0/lib/active_record/migration.rb:777:在“up”中

最佳答案

https://www.postgresql.org/docs/current/static/sql-syntax-lexical.html
系统使用的标识符不超过NAMEDATALEN-1字节；
较长的名称可以在命令中写入，但它们将被截断。
默认情况下，NAMEDATALLN为64，因此最大标识符长度为63。
字节。如果这个限制有问题，可以通过更改
src/include/pg_config_manual.h中的NAMEDATALEN常量。
所以除非你真的想重新编译，否则63是标识符的硬限制

关于ruby-on-rails - 索引名称“index_name”太长；限制为63个字符，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/50128995/