{
  "slug": "idempotency",
  "term": "Idempotency",
  "aliases": [
    "Idempotence"
  ],
  "definition": "Idempotency is the property that repeating the same operation with identical inputs has the same intended effect as performing it once.",
  "note": "HTTP idempotency does not require identical responses or prohibit a separate log entry for each attempt (RFC 9110, section 9.2.2). It is not a durability or exactly-once execution guarantee. Repeating an assignment after another writer changes the value can overwrite that intervening update; duplicate suppression and concurrency control address distinct concerns.",
  "related": [
    "idempotency-key",
    "retry-deduplication",
    "io-timeout"
  ],
  "citations": [
    {
      "id": "http-idempotency",
      "title": "RFC 9110: HTTP Semantics (June 2022), section 9.2.2, Idempotent Methods.",
      "url": "https://www.rfc-editor.org/rfc/rfc9110.html#section-9.2.2",
      "accessed": "2026-10-15"
    },
    {
      "id": "hesela-timeouts",
      "title": "Storage timeouts: an expired timer is not a cancelled write",
      "url": "https://hesela.com/analyses/storage-timeouts-uncertain-completion/",
      "accessed": "2026-10-15"
    }
  ],
  "status": "shipping",
  "advantages": [],
  "limitations": [],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-10-15"
}