does ruby on rails automatically lock active record associations when locking the active record?

Pretty basic question:

I have a model x that has_many y, and model y belong_to x.

If I lock an instance of 开发者_JAVA技巧model x with id x_id, does it also lock the associated rows in the table for model y which has has value x_id under the join column?

Or does ror locking just lock the active record and does not care about its associations?

Thanks!

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From what i know, it would not lock any associations. It just locks rows, without caring for model associations.

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It seems as if there are two locking strategies in rails, optimistic (which doesn't actually lock rows but ActiveRecord raises ActiveRecord::StaleObjectError for multiple updates to the same row [except the first update, which will succeed]), and pessimistic (which appends FOR UPDATE to the select statement and actually locks the rows (assuming your database supports locking). None of the ActiveRecord Locking documentation I read through implies that there is any magic that causes/allows associative records to be locked.

Since you can pass your own locking clause, I would suggest on reading up on how your specific database handles the clause rails uses for pessimistic locking (select ... for update) and other clauses that you can pass (Using ActiveRecord#lock!).