What do you find so rediculously good about this? I find it complicated. If I understood it properly, it's just making inserts asynchrounous (removing durability) and batches data into single statement (removing atomicity). Or did I miss something?
"This property of ACID is often partly relaxed due to the huge speed decrease this type of concurrency management entails."
Indeed.
If you have the viewpoint that DB validation is for catching programming errors, not invalid data (i.e. you validate everything before it hits DB anyway), this relaxation can be reasoned about client-side anyway.
Of course, it's quite likely an acceptable trade-off for for these records. Relational DBs sold everyone on ACID in the 90's, but a lot of data doesn't really deserve its cost. He hasn't found a way around Brewer's Conjecture (and I wish I had a nickel for every time it's rediscovered :-).
Things in the queue get acknowledged - and sometimes resultsets or IDs returned, in the case of SELECT and INSERTs that return auto keys.
I think this is a good method, as long as you're careful about these things. (I assume you've taken care of them, just talking about this method in general).
1) If there were multiple transactions in the web request, previously the second ones likely wouldn't have been run if the first were to fail. This would likely change that and it could even necessitate having rollback for the second transaction.
2) Now there is a potential "thundering herd" problem. When the transaction batch commit notification is received, all 1000 web requests made over that 100 ms period become ready to execute and start competing for network/disk/database resources simultaneously. A disk that was just sitting idle now has 1000 different things to do at once. If everybody hits the network at once it can cause temporary packet loss. When packets are lost, connections can be dropped or delayed by retransmits. Sometimes client retries and retransmits can happen synchronously. In the worst case, such a system can end up oscillating wildly between excessive load and excessive idle.
Yes, you do have to be careful about saturating links generally. The thundering herd thing is a rich man's problem :)