Ruby on Rails

worth noting, since I could have '000's of records, the point of this is to avoid having to load the ids I want to delete into the app and let the DB optimize for it.

On Thursday, March 29, 2012 1:52:45 PM UTC-7, John Hinnegan wrote:

Hi all,

I have a table where I'm deleting sparse records -- basically cleaning up broken has_many / belongs_to relationships. (How we get into this situation is a trade-off. We can have '000's of records, and deletes generally happening during peak load, so we just do the clean up later.)

I have ModelA and ModelB. ModelB belongs_to ModelA. ModelA has_many ModelB

Anyway, I have figured out the SQL I want (MySQL:

    DELETE                                                                                                                             

      model_a_table                                                                                                  

    FROM                                                                                                                               

      model_a_table                                                                                                  

      left join model_b_table on model_a_table.model_b_id = model_b_table.id                     

    WHERE                                                                                                                              

      model_b_table.id is NULL;                       

I believe I have the equivalent SELECT figured out as:

ModelA.includes(:model_b).where(:model_b => {:id => nil})

However, I can't seem to get the equivalent delete working. Adding delete_all to the end of the relationship 'breaks' the includes and causes the where to fail.

I'm going to try and figure this out with the old syntax (ModelA.delete(:conditions...)). Thought I'd ask here first as it seems like I should be able to pretty easily convert the SELECT I have to an equivalent delete operation.

Thanks in advance.

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