Comment by blintz
3 years ago
Wasn’t me, but it was accurate!
Indeed, except in some (exciting!) new theoretical constructions, server work is always linear in the database size.
However, I’d emphasize that our work shows that the constabt factor on this linear operation is really high. We process at 300MB/s to 1.9GB/s on a single core, which is fast enough for relatively large databases. Remember that the computation is embarrassingly parallel, so you can always throw more compute at larger databases. To summarize, we think the speed is now fast enough that it really can be feasible to scan the whole database to answer a single query.
> except in some (exciting!) new theoretical constructions
Sorry if this is too much of a tangent, but I would love to know what these are!
They are called PIR with sublinear online computation or offline/online PIR.
Key idea is the client issues a query that is independent of what they really want. This is the “offline” query. This query is linear (unavoidable) and the client gets some hints as a result
Then later, the client can issue one or more queries for elements they want and those queries can be sublinear in terms of computation. The client uses hints to make that happen.
Some papers on this are:
https://eprint.iacr.org/2019/1075.pdf
https://eprint.iacr.org/2021/1438
https://eprint.iacr.org/2022/081.pdf
Sure! This paper has people really excited from a theoretical standpoint: https://eprint.iacr.org/2022/081.pdf. It’s a bit far from practical for single-server, but I’m sure people are working on it.