At Microsoft we were scaling SQL Server up to 10-100k rows per second on OLTP $20k systems with a hot cache and RAIDed HDDs.
In one of the code-word projects I saw an $25k system with an OLTP dataset do 1 billion rows in a second.
Edit: We also had statistics that said that 90% of our customers had less than 100GB of data. 99% had < 1 TB. The vast majority of database users shouldn't even be thinking about looking at non-RDBMS systems.
I agree with all of that. But the original poster was claiming 10k SELECTs/second on a 10TB data set. That just sounds fishy to me.
If your dataset fits in memory on one node, I'm all about using a database (prefer MySQL personally, might look at postgres now that it finally has replication).
In one of the code-word projects I saw an $25k system with an OLTP dataset do 1 billion rows in a second.
Edit: We also had statistics that said that 90% of our customers had less than 100GB of data. 99% had < 1 TB. The vast majority of database users shouldn't even be thinking about looking at non-RDBMS systems.