I wrote a longer reply, but it buried the lead. So let's focus on the main issue I spotted: > In your approach you're going to have 500 keys in memory as well

I wrote a longer reply, but it buried the lead. So let's focus on the main issue I spotted: > In your approach you're going to have 500 keys in memory as well. That's not true at all. At no point I have 500 of anything in memory. So there's some big misunderstanding here about what I propose (and hence how it compares with your alternative). If you want to go over my original comments again and ask questions to understand the concept, I'm at your service.