| --- |
| license: cc-by-4.0 |
| pretty_name: Software Heritage content bloom filters |
| --- |
| |
| # Software Heritage content membership filters |
|
|
| DCSO-format bloom filters over the content hashes of **all 29,283,034,124 |
| content blobs** in the [Software Heritage](https://www.softwareheritage.org/) |
| archive (graph dataset export 2026-06-04, `content` table), one |
| filter per hash scheme, false-positive rate p = 0.0001 each: |
|
|
| | file | keyed on | key encoding | |
| |---|---|---| |
| | `swh.sha256.bloom` | sha256 | lowercase hex | |
|
|
| `sha1_git` is the git blob id — membership testing straight from a git |
| object id, no file bytes needed. |
|
|
| Ask "has SWH archived this content?" without touching the rate-limited |
| API — then confirm hits at |
| `https://archive.softwareheritage.org/api/1/content/<scheme>:<hex>/`. |
| Built for [hashdex](https://github.com/davidar/hashdex) (`hdx scan`), |
| readable by any DCSO/hashlookup-compatible bloom implementation |
| (header: LE u64 version, n, p-bits, k, m, N; then bit array; |
| membership = FNV-1 64 mod 2^64-87, k rounds of wrapping multiply by |
| 18446744073709550147 mod 2^64-87, bit index mod m). |
|
|
| Derived from the Software Heritage graph dataset (CC-BY 4.0, |
| attribution: Software Heritage). See their |
| [dataset docs](https://docs.softwareheritage.org/devel/swh-export/graph/dataset.html). |
|
|
