{
  "slug": "pbs-t-visibility",
  "term": "PBS t-visibility",
  "aliases": [
    "Probabilistically bounded time visibility"
  ],
  "definition": "PBS t-visibility describes a probabilistic guarantee that a read started at least t after a write commits includes that write's version or a newer one.",
  "note": "This is the 2012 PBS time-based formulation; the reference event is write commit, not submission. Its estimates require a propagation model and do not impose a deterministic visibility deadline. [pbs-2012]\n\nThe later journal treatment separates time-based regular and atomic semantics. A result about freshness is not automatically a result about atomic read ordering. [pbs-2014]\n\nA version-count distribution alone cannot determine elapsed-time freshness. Hesela's count-mixture example deliberately supplies no message-delay distribution and makes no time-visibility claim. [hesela-mixture]",
  "related": [
    "partial-quorum",
    "pbs-k-staleness",
    "eventual-consistency",
    "replication-lag"
  ],
  "citations": [
    {
      "id": "pbs-2012",
      "title": "Bailis et al. Probabilistically Bounded Staleness for Practical Partial Quorums. PVLDB 5(8), 776-787 (2012), sections 3.1-3.4. DOI: 10.14778/2212351.2212359.",
      "url": "https://www.vldb.org/pvldb/vol5/p776_peterbailis_vldb2012.pdf",
      "accessed": "2026-11-11"
    },
    {
      "id": "pbs-2014",
      "title": "Bailis et al. Quantifying eventual consistency with PBS. The VLDB Journal 23, 279-302 (2014), sections 2.2-2.3, 4.1-4.2. DOI: 10.1007/s00778-013-0330-1.",
      "url": "https://www.bailis.org/papers/pbs-vldbj2014.pdf",
      "accessed": "2026-11-11"
    },
    {
      "id": "hesela-mixture",
      "title": "Hesela: exact version-count mixtures, assumptions and executable source hashes.",
      "url": "https://hesela.dev/research/pbs-count-mixtures.json",
      "accessed": "2026-11-11"
    }
  ],
  "status": "research",
  "advantages": [],
  "limitations": [
    {
      "text": "The probability depends on a stated model; no particular production failure rate or deterministic bound is implied.",
      "citationIds": [
        "pbs-2012",
        "pbs-2014"
      ]
    }
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-11-11"
}