Quiz Entry - updated: 2026.07.30
Roughly how do permissionless blockchains, permissioned blockchains, and central databases compare on performance and structure?
Throughput and latency get better as you move from permissionless → permissioned → central DB; the blockchains' cost buys tolerance of untrusted writers, which the central DB has zero of.
| Permissionless | Permissioned | Central DB | |
|---|---|---|---|
| Throughput | Low | High | Very high |
| Latency | Slow | Medium | Fast |
| Untrusted writers tolerated | High | Low | 0 |
| Consensus | Mainly PoW, some PoS | BFT (e.g. PBFT) | None |
| Centrally managed | No | Yes | Yes |
The single idea behind the table: consensus is what costs you performance. A permissionless chain runs heavy consensus (PoW) to tolerate many anonymous, untrusted writers, so it's slowest. A permissioned chain uses lighter BFT consensus among few known writers, so it's faster. A central DB does no consensus at all — fastest, but tolerates no untrusted writers because there's only one.
Go deeper:
Consensus (computer science) (Wikipedia) — why PoW vs BFT vs no-consensus is exactly what buys (or forfeits) tolerance of untrusted writers.