Consequent attribute calculations with a queuing system
- by vrinek
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?
