I agree that your PG numbers don't sound likely/factual -- the reason for your confusion is probably that somebody gave you untrue performance numbers for postgres or you're not comparing the same things. Is the 1m+ TPS something you measured yourself or "heard from a friend"?
If you ran the benchmark yourself, how did you achieve 1m durable writes/sec on a postgres machine/instance? [It's quite an achievement] On what kind of crazy hardware? How large was each write/row? Did you use the postgres network protocol to perform the writes?
By extrapolation writes are IO bound you don't need crazy expensive things to get to the needed number of IOPS Intel 750 is 230,000 random writes @ $320 per PCI-E SSD. 9 drive
config is over 2,000,000 IOPS for less than 3K.
Yeah it's a bit more complex than that... The disk "IOPS" number on the box doesn't translate 1:1 or even linearly to number of committed durable transactions per second. You should try this with postgres and see how it goes.
If you ran the benchmark yourself, how did you achieve 1m durable writes/sec on a postgres machine/instance? [It's quite an achievement] On what kind of crazy hardware? How large was each write/row? Did you use the postgres network protocol to perform the writes?