{
  "slug": "lsm-trie",
  "term": "LSM-trie",
  "aliases": [],
  "definition": "LSM-trie is a hash-routed, multi-level key-value store that groups lookup filters to limit out-of-memory metadata reads.",
  "note": "Routing: hash prefixes select table containers; suffixes select buckets. Grouped filters cover the same bucket position across sub-levels. Native ordered range search is not supported. [lsm-trie-paper]\n\nLookup: the pinned implementation checks active tables before traversing containers, where filter bits select candidate tables. A positive candidate still requires full-key verification. [lsm-trie-db] [lsm-trie-table]",
  "related": [
    "lsm-tree",
    "bloom-filter",
    "read-amplification"
  ],
  "citations": [
    {
      "id": "lsm-trie-paper",
      "title": "Wu, Xu, Shao and Jiang. LSM-trie. USENIX ATC 2015, pp. 71-82; sections 2.3-2.4, Table 1.",
      "url": "https://files.usenix.org/s3fs-public/cdn/atc15-paper-wu.pdf",
      "accessed": "2026-11-11"
    },
    {
      "id": "lsm-trie-db",
      "title": "LSM-trie author code: recursive_lookup and db_lookup, pinned revision.",
      "url": "https://github.com/wuxb45/lsm-trie/blob/8e2fca33a43749bf3d82ceb6f6a2264fb12f97a0/db.c#L1068-L1134",
      "accessed": "2026-11-11"
    },
    {
      "id": "lsm-trie-table",
      "title": "LSM-trie author code: full-key equality and recursive bucket lookup, pinned revision.",
      "url": "https://github.com/wuxb45/lsm-trie/blob/8e2fca33a43749bf3d82ceb6f6a2264fb12f97a0/table.c#L944-L1104",
      "accessed": "2026-11-11"
    },
    {
      "id": "hesela",
      "title": "Hesela: LSM-trie, cold metadata and false-positive counts.",
      "url": "https://hesela.com/analyses/bloom-filters-lsm-read-cost/#lsm-trie-metadata",
      "accessed": "2026-11-11"
    }
  ],
  "status": "research",
  "advantages": [],
  "limitations": [
    "The two-read design assumes resident upper-level metadata; false positives and bucket migrations can add reads. [lsm-trie-paper]"
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-11-11",
  "provenance": [
    "Full paper and pinned lookup code reviewed. No engine execution or benchmark reproduction."
  ]
}