{
  "slug": "memento-range-filter",
  "term": "Memento Filter",
  "aliases": [
    "Memento range filter"
  ],
  "definition": "Memento Filter is a dynamic approximate range-emptiness structure that combines hashed key prefixes with ordered key suffixes.",
  "note": "The suffixes, called mementos, locate keys inside fixed-width partitions. Insertions, deletions and expansion distinguish the design from static SuRF. Choosing r = ceil(log2(R)) suffix bits bounds an inclusive range of at most R integer positions (R >= 2) to two partitions. Longer queries are supported with additional probes, not the same two-partition cost. [memento-paper]\n\nThe pinned C API returns 0 for a negative query and 1 or 2 for a positive query; 2 additionally indicates possible fingerprint rejuvenation. A positive result still requires an exact backing-store check. [memento-api]\n\nThe later Diva evaluation uses a modified Memento baseline with Aleph-style expansion; its measurements must not be attributed to the unmodified original artifact. [diva-comparison]",
  "status": "research",
  "advantages": [],
  "limitations": [
    {
      "text": "The author header warns that its concurrency features have not been thoroughly tested; API declarations are not an independent concurrency validation.",
      "citationIds": [
        "memento-api"
      ]
    }
  ],
  "related": [
    "proteus-range-filter",
    "grafite-range-filter"
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "citations": [
    {
      "id": "memento-paper",
      "title": "Eslami and Dayan. Memento Filter. PACMMOD 2(6), article 244 (2024). DOI: 10.1145/3698820; sections 4-7, arXiv v3.",
      "url": "https://arxiv.org/html/2408.05625v3",
      "accessed": "2026-11-14"
    },
    {
      "id": "memento-api",
      "title": "Memento Filter public API: query results, resizing and concurrency disclaimer; commit ded520cebdabfb3f3d640d838c0aee44636453e2.",
      "url": "https://github.com/n3slami/Memento_Filter/blob/ded520cebdabfb3f3d640d838c0aee44636453e2/include/memento.h",
      "accessed": "2026-11-14"
    },
    {
      "id": "diva-comparison",
      "title": "Eslami, Bercea and Dayan. Diva: Dynamic Range Filter for Var-Length Keys and Queries. PVLDB 18(11), 2025; sections 2, 5.2. DOI: 10.14778/3749646.3749664.",
      "url": "https://www.vldb.org/pvldb/vol18/p3923-eslami.pdf",
      "accessed": "2026-11-14"
    },
    {
      "id": "hesela-memento",
      "title": "Hesela: Memento range length and query-result contracts",
      "url": "https://hesela.com/analyses/bloom-filters-lsm-read-cost/#memento-contract",
      "accessed": "2026-11-14"
    }
  ],
  "updated": "2026-11-14",
  "provenance": [
    "Primary-paper and pinned-source review only; no Memento execution, benchmark reproduction or concurrency experiment. Distinct from the PLDI 2023 Memento persistent-memory framework."
  ]
}