KV Store

Globally-replicated KV Store

The fastedge::kv module is a key/value store that is globally replicated across every edge location where FastEdge runs. Reads are served locally with sub-millisecond latency; writes go to a central source-of-truth and propagate to every edge automatically.

Architecture and propagation

Unlike CDN solutions that run a single data store at a regional point of presence, FastEdge KV deploys a storage instance at every edge location where your application runs. Your WASM component and its KV instance live in the same environment, so reads do not cross the network — they resolve locally with sub-millisecond latency.

Writes follow a write-once, replicate-everywhere model. When you write through the Gcore API, the value is first persisted to a central source-of-truth, then replicated automatically to every edge KV instance worldwide. Global replication typically completes within 1–2 seconds.

This makes the store eventually consistent: during the propagation window, a read served from a different edge than the one that performed the write may return a stale value, or null for a freshly written key. Reads from the same edge see the new value immediately.

When to use KV vs Cache

The architecture is tuned for read-heavy, infrequently-written data — configuration, feature flags, content fragments, allow/deny lists keyed by IP, IP subnet, or ASN, lookup tables, and sorted sets.

Property	fastedge::kv	fastedge::cache
Scope	All edges (globally replicated)	One POP
Consistency	Eventual; ~1–2s propagation	Strong within a POP
Atomic counters	Not available	incr, decr, getOrSet coalescing
Persistence	Durable across deployments	Evicted; no durability guarantee
Typical use	Configuration, lookup tables, sorted sets	Rate limits, counters, response memoising

If your workload needs strong consistency on every read — atomic counters, rate limits, quotas, request coalescing — use fastedge::cache instead.

Importing

Open a store by name with KvStore.open(), then call instance methods on the returned handle.

import { KvStore } from 'fastedge::kv';

async function eventHandler(event) {
  const store = KvStore.open('kv-store-name-as-defined-on-app');
  const value = store.get('greeting');
  return new Response(value ?? 'not found');
}

addEventListener('fetch', (event) => {
  event.respondWith(eventHandler(event));
});

See KvStore.open() for the open API, and the KV Instance pages for get/scan, sorted-set, and Bloom-filter operations.