{
  "slug": "prefix-extractor",
  "term": "Prefix extractor",
  "aliases": [
    "Key prefix transform"
  ],
  "definition": "A key transformation with a defined input domain that produces the prefix used for prefix-based indexing or filtering.",
  "note": "RocksDB's SliceTransform contract distinguishes keys inside its domain and constrains compatibility with comparator ordering. A fixed-length extractor and a capped-length extractor handle short keys differently; do not infer a bytewise query contract from a character count. [prefix-transform]",
  "related": [
    "prefix-bloom-filter",
    "bloom-filter"
  ],
  "citations": [
    {
      "id": "prefix-transform",
      "title": "RocksDB v9.7.3. SliceTransform: domain, ordering and prefix-extraction contracts.",
      "url": "https://github.com/facebook/rocksdb/blob/v9.7.3/include/rocksdb/slice_transform.h",
      "accessed": "2026-10-13"
    },
    {
      "id": "hesela",
      "title": "Hesela: filter predicates, prefix correctness and SuRF boundaries",
      "url": "https://hesela.com/analyses/bloom-filters-lsm-read-cost/#predicates",
      "accessed": "2026-10-13"
    }
  ],
  "status": "shipping",
  "advantages": [],
  "limitations": [],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-10-13"
}