DB/2. Not the best, but it's inbuilt, and accessible with system utilities/calls, using any language on the system, including control language.
Say what you will but DB/2 on IBM i is the most SQL compliant database of any. It scales well and being built into the system means tuning it is not often needed. In addition there is near zero database administrative effort required for most IBM i systems. Since all disk space is typically viewed as a single store, space for tables and collections is automatically drawn from and returned to that space.
If you simply change everyone's temporal frame of reference by the exact same amount, you have done nothing, really. Everyone will simply account for the 500ms delay, and trades will still execute in the same order.
Exactly. So look up IEX. Their solution is to 'position' themselves electronically to be *EXACTLY the same number of ms away from all the major exchanges in the U.S. So when they execute trades across 5 exchanges they all happen at EXACTLY the same time on all the exchanges. Thus those HFT guys react too late, all the needed buys for the specific transaction have already occurred. HFT Guys loose. Bummer.
It's not all about speed it's about timing.
"If I do not want others to quote me, I do not speak." -- Phil Wayne