# datacrypt-project/hitchhiker-tree

Functional, persistent, off-heap, high performance data structure

Repository: https://github.com/datacrypt-project/hitchhiker-tree
Canonical: https://ross.abutalabs.com/products/hitchhiker-tree
Language: Clojure
License: EPL-1.0
License Family: copyleft
Last push: 2018-07-22T21:01:33+00:00

## Health v2 (maintenance only)
Score: 32/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 0, release rhythm 35, longevity 100
- inputs: {"age_days": 3848, "days_push": 2964, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1217, forks 63 (observed 2026-08-28T04:04:01.502003+00:00)

## What it is
A Clojure library implementing hitchhiker trees, a functional, persistent sorted key-value data structure combining fractal trees with immutable data structures. It supports incremental persistence, lazy loading from pluggable backing stores, and snapshotting, with an included Redis-backed storage layer (Outboard).

## Use cases
- store sorted key-value data larger than JVM heap in Clojure
- persist an in-memory data structure incrementally without full serialization
- create cheap immutable snapshots of a large dataset for querying
- fork a persistent data tree like a git repository
- build a scalable open-source Datomic-like storage backend
- restart an application without reloading all data from scratch

## When to choose
- you're in Clojure/JVM and need a persistent, snapshottable sorted map beyond memory limits
- you want incremental persistence with lazy loading from a custom backing store
- you need functional/immutable semantics at large scale

## When to avoid
- you need a production-grade, actively maintained database
- you're outside the Clojure/JVM ecosystem
- you need rich query features beyond sorted key-value lookups

## Facets
- artifact type: library
- maturity: maintenance
- function: database, serialization, caching
- domain: databases, developer-tools
- platform: jvm, jvm-scripting
- tags: clojure, persistent-data-structures, sorted-map, fractal-trees, snapshots, functional-data-structures, off-heap, redis-backend, data-engineering

## Member repositories
- datacrypt-project/hitchhiker-tree (main) score 32

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:04:01.502003+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T06:17:07.347208+00:00, confidence not recorded.
  - readme: https://github.com/datacrypt-project/hitchhiker-tree (fetched 2026-08-28T04:04:01.502003+00:00, sha 32030c3cf37c)
- Data as of 2026-08-30T08:39:29.467469+00:00.