Strong Consistency
ELI5 — The Vibe Check
Strong consistency means the moment you write something, everyone everywhere immediately sees the updated value. No 'give it a sec' nonsense. It's more expensive and slower because servers need to coordinate before confirming your write, but when you're dealing with money or inventory, 'eventually' isn't good enough.
Real Talk
Strong consistency (linearizability) guarantees that once a write completes, all subsequent reads from any node will return the updated value. It requires coordination between replicas, typically through consensus protocols like Raft or Paxos, adding latency to write operations. Databases like CockroachDB, Spanner, and FaunaDB provide strong consistency across distributed nodes.
When You'll Hear This
"Banking transactions require strong consistency, not eventual." / "Strong consistency adds latency but eliminates stale reads."
Related Terms
CAP Theorem
The CAP theorem says a distributed database can only guarantee two out of three things: Consistency (everyone sees the same data), Availability (every requ...
Consensus Algorithm
A consensus algorithm is how a group of servers democratically agree on something even when some of them are flaky or unreachable.
Eventual Consistency
Eventual consistency means 'give it a moment and everything will match up.' You write data to one server, and the other servers will get the update...
Serializable Isolation
Serializable isolation is the strictest mode where the database pretends all transactions run one after another, even though they're actually concurrent.