I am hoping someone can point to on how to benchmark my lucense RAMDirectory index?
I have about 300-500K documents indexed (less than 80 characters per document) and I want to benchmark how fast the in-memory RAMDirectory is.
At a very high level, should this be tens or hundreds of queries per second?
Too many variables to even guess. What kind of queries you're running, your hardware, the makeup of your index, etc. That can make orders of magnitude of difference, so even a high-level guess would be meaningless.
You can take a look at Lucene's nightly benchmarks though, which use the Wikipedia English export (a much larger dataset than yours, of course, but it's something).