mysql,ruby-on-rails,rdbms , Can Rails deal with DB uniqueness without index?


Can Rails deal with DB uniqueness without index?

Question:

Tag: mysql,ruby-on-rails,rdbms

I see add_index ~ unique: true statement in schema.rband think uniqueness is constraint for table, not for index.Using index is one of way realizing uniqueness, Programmer should not designate to the RDBMS "how" and index quicken searching but take costs inserting. In fact, is there another way to keep uniqueness constraint? If not, why Rails provide us only add_index statement for uniqueness constraint?


Answer:

Because there is no need for other ways. Under the hood it's all the same: when you define a UNIQUE constraint, a UNIQUE index is created on that table to enforce it.

I haven't found the related cite for MySQL in an authoritative source, but "rumors are everywhere".


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