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I have a product model and orders associated to the product. I wanted to analyze all orders from creation of product to current time. I was thinking to optimize, I would take products created at day, and current time as start and end points. The next step would be to automatically pull 10 equally spaced times between start and current time and place them in an array. For each one of these dates, query orders for the 10 dates provided.

Question is, is this the best approach to analyzing order data / performance on the query? If so, how do you pull the 10 dates in between the created at and current time range in Rails.

I have the following pseudocode --

Products.where(event_id: event)[Products.where(event_id: event).first.created_at.to_i..Time.now.to_i)].each_slide(10) do |p|
  # Loop through orders of the 10 pulled days
  Orders.where(product_id: p.id).each do |o|
    # Add products to one of the 10 pulled days
  end
end
Yasir
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  • do you mean, getting the last 10 records based current time and created_at of "products", I mean in between the 2 date times? – aldrien.h Feb 05 '16 at 02:03
  • in this case, 10 dates in between created_at and now. once I have the 10 equally distant dates, I'll loop through each to get orders for that day – Yasir Feb 05 '16 at 02:07

1 Answers1

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Example Pseudocode:

1st Getting the last Product's created_at value

require 'date'
prod_date = Products.where(event_id: event).last.created_at
prod_date = prod_date.to_time.strftime("%Y-%m-%d %H:%M:%S")

2nd Getting last 10 records in products table based on prod_date & date_today.

date_today = DateTime.now.strftime("%Y-%m-%d %H:%M:%S")
Products.where('event_id ? AND (created_at BETWEEN ? AND ?)',  event, prod_date, date_today).limit(10)

You can also arrange it if you want by adding e.g. .order("created_at DESC")

3rd Start to iterate with you orders data from the result above.

Orders.where(product_id: p.id).each do |o|
   # Add products to one of the 10 pulled days
end

====================================

I understand want you plan to do. Honestly I haven't tried that. But, my idea for that is, for ex. you have 10 data & you want to get 3 equally spaced values.

Why not try to iterate it by 3 (but get the first value). 

Imagine this is your data: 1 2 3 4 5 6 7 8 9 10

get the first = 1
iterate the next by (3) = 4, 7, 10
Result = 1, 4, 7, 10

You may need to get the first & last data, depends on how many

3 equally spaced values

you want to get from total result count.

aldrien.h
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  • this is great! thanks for the breakdown it makes sense. the one difference is, instead of the last 10 records, I wanted to get 10 records equally separated from creation to current date. i was stuck on this part – Yasir Feb 05 '16 at 02:30
  • Glad to help you! Happy programming! – aldrien.h Feb 05 '16 at 02:33
  • sorry, was asking, if there was a way to get 10 dates in the range equally distant from start and current date vs last 10? – Yasir Feb 05 '16 at 02:38
  • i'm a little bit confused with your "range equally distant" , what's that fully means? 2 dates are equal/same? – aldrien.h Feb 05 '16 at 02:42
  • sorry, lets say you have 0 as start, and 10 as end. and ask for 3 equally spaced values in between that. it would then be 2.5, 5, 7.5. which would make the range [0, 2.5, 5, 7.5, 10]. ideally, i want to capture this subset, pull orders for those days specifically to compare – Yasir Feb 05 '16 at 02:47