Consequent attribute calculations with a queuing system
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Published on 2012-03-12T08:49:33Z
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2012/03/24
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For all of the following assume these:
- rails v3.0
- ruby v1.9
- resque
We have 3 models:
- Product belongs_to :sku, belongs_to :category
- Sku has_many :products, belongs_to :category
- Category has_many :products, has_many :skus
When we update the product (let's say we disable it) we need to have some things happen to the relevant sku and category. The same is true for when a sku is updated.
The proper way of achieving this is have an after_save
on each model that triggers the other models' update events.
example:
products.each(&:disable!)
# after_save triggers self.sku.products_updated
# and self.category.products_updated (self is product)
Now if we have 5000 products we are in for a treat. The same category might get updated hundreds of times and hog the database while doing so.
We also have a nice queueing system, so the more realisting way of updating products would be products.each(&:queue_disable!)
which would simply toss 5000 new tasks to the working queue. The problem of 5000 category updates still exists though.
Is there a way to avoid all those updates on the db?
How can we concatenate all the category.products_updated for each category in the queue?
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