> Can this really be too much lock contention for a single database row?
When you consider how many other (often poorly-crafted) DB queries and service calls are being performed while holding the row locked, yes, it can rapidly add up. If the entire pipeline takes 500 msec, congratulations, you can’t sell more than 2 units per second of that SKU. If the item is popular and being actively hyped, then yes, that can be a problem.
When you consider how many other (often poorly-crafted) DB queries and service calls are being performed while holding the row locked, yes, it can rapidly add up. If the entire pipeline takes 500 msec, congratulations, you can’t sell more than 2 units per second of that SKU. If the item is popular and being actively hyped, then yes, that can be a problem.