I am confused about how Magento 2 inventory works when an order is placed. What if I have only one qty stock for a product and there are two people who make an order for this product at the same time. What happens when the product is added to the cart? Will the stock get reduced?
The deafult behavior is that the stock is reserved when the order is placed (not when the product is added to the cart). Only the first customer will be able to finish checkout process. Right after order placement quantity remains the same BUT saleable quantity decreases (in your case qty = 1 and saleable qty = 0). When you ship the order the qty decreases. When you cancel the order, saleable qty increases back to 1.
Salabel quantity work flow :
Let’s assume that product is : 24-MB01
There are 2 warehouse : 1) India 2) USA
Now we have 20 products in stock and 20 salable products where, India warehouse has 12 qty and USA warehouse has 8 qty.
1 customer bought 5 items of the 24-MB01 product. So, there are 5 items will be reserve to be deliver. That’s why now salable qty will be 15 (20 – 5 = 15) & qty will be 20
Before invoice create, That customer return 3 items from 5 items which they order items. The salable qty is the sum of all reservation of that product. That’s why now salable qty will be 18 (20 – 5 + 3 = 18) where 20 is total qty, 5 is order items and 3 is return order items.
After invoice create and shipment create, you need to reindex and then, 2 qty will be decrease from qty column. Now, qty will be 18 and salable qty will be 18.
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