如何在使用MySQL的Ruby on Rails迁移中处理太长的索引名称？ [英] How do I handle too long index names in a Ruby on Rails migration with MySQL?

问题描述

我正在尝试添加一个唯一索引，该索引是从四个关联表（用户，大学， subject_names ）的外键创建的， subject_types ）：

I am trying to add an unique index that gets created from the foreign keys of four associated tables (users, universities, subject_names, subject_types):

add_index :studies, ["user_id", "university_id", \
          "subject_name_id", "subject_type_id"],
          :unique => true

MySQL对索引名称的限制导致迁移停止。以下是错误消息：

MySQL's limitation for the index name causes the migration to stop. Here is the error message:

表'研究'上的索引名称'index_studies_on_user_id_and_university_id_and_subject_name_id_and_subject_type_id'太长;限制为64个字符

Index name 'index_studies_on_user_id_and_university_id_and_subject_name_id_and_subject_type_id' on table 'studies' is too long; the limit is 64 characters

我该如何处理？我可以使用别名吗？

How can I handle this? Can I use an alias?

推荐答案

使用：

add_index :studies, ["user_id", "university_id", \
          "subject_name_id", "subject_type_id"], 
          :unique => true, :name => 'my_index'

更多信息请参见 add_index 。

More information is in add_index.

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