Customers placed orders for product and I see salable quantity goes down. But quantity remains the same. What to do while these values were the same?
This is expected behaviour.
Initially both quantity and salable quantity is same for any product. When you will receive any order the salable quantity decreases but quantity remains unchanged. When shipment is created or order is cancelled then again both the quantity and salable quantity will become same.
When you receive the order, a new entry happens in inventory_reservation table with ordered quantity of the sku.
Salable quantity is calculated based on below logic:
salable quantity = qty + (sum of quantity in inventory_reservation table for that sku)
Let's say initially quantity and salable quantity was 10 for a sku.
When one order will be placed with 2 quantity, a new entry will happen in inventory_reservation table with -2 value against quantity field.
So salable quantity will become 10 + (-2) = 8
Again when shipment will be created for this order, +2 entry will happen in inventory_reservation table and quantity will also decrease by 2.
So quantity will be 8. salable quantity will be 8 + (-2) + (+2) = 8.
So in the final stage both quantity and salable quantity will become same.