# @comunica/actor-rdf-metadata-extract-hydra-count

> A hydra-count rdf-metadata-extract actor

Latest version **5.4.0** (published 2026-09-14) · MIT license · 0 weekly downloads

## Install

```sh
npm install @comunica/actor-rdf-metadata-extract-hydra-count
pnpm add @comunica/actor-rdf-metadata-extract-hydra-count
yarn add @comunica/actor-rdf-metadata-extract-hydra-count
bun add @comunica/actor-rdf-metadata-extract-hydra-count
```

## Health

**Score 60/100 (C)** — status: active.

Positive: has types; no vulnerabilities; recently updated; high maintenance score.

Warnings: low downloads; no esm support.

## Facts

| | |
|---|---|
| Version | 5.4.0 |
| Published | 2026-09-14 |
| First published | 2018-03-19 |
| Weekly downloads | 0 |
| License | MIT |
| TypeScript types | bundled |
| Module format | CommonJS |
| Dependencies | 2 |
| Unpacked size | 25.1 KB |
| Known vulnerabilities | 0 |
| Install scripts | no |
| GitHub stars | 583 |
| Maintainers | joachimvh, rubensworks, rubenverborgh, dexagod, jeswr |
| Keywords | comunica, actor, rdf-metadata-extract, hydra-count |

## Links

- npm: https://www.npmjs.com/package/@comunica/actor-rdf-metadata-extract-hydra-count
- Repository: https://github.com/comunica/comunica
- Homepage: https://comunica.dev/
- Issues: https://github.com/comunica/comunica/issues
- Funding: https://opencollective.com/comunica-association
- npm.io page: https://npm.io/package/@comunica/actor-rdf-metadata-extract-hydra-count

## Dependencies (2)

- [@comunica/core](https://npm.io/package/@comunica/core.md) ^5.4.0
- [@comunica/bus-rdf-metadata-extract](https://npm.io/package/@comunica/bus-rdf-metadata-extract.md) ^5.4.0

## Recent versions

- 5.4.0 (latest) — 2026-09-14
- 4.4.2-alpha.49.0 (next) — 2025-10-22
- 5.3.0 — 2026-07-10
- 5.2.3 — 2026-05-26
- 5.2.2 — 2026-05-03
- 5.2.0 — 2026-04-14
- 5.1.3 — 2026-01-30
- 5.1.0 — 2026-01-16
- 5.0.3 — 2026-01-12
- 5.0.2 — 2026-01-12
- 5.0.0 — 2026-01-08
- 4.5.0 — 2025-11-18
- 4.4.0 — 2025-09-17
- 4.2.0 — 2025-04-29
- 4.1.0 — 2025-02-11
- … 99 more at https://npm.io/package/@comunica/actor-rdf-metadata-extract-hydra-count/versions

## README

# Comunica Hydra Count RDF Metadata Extract Actor

[![npm version](https://badge.fury.io/js/%40comunica%2Factor-rdf-metadata-extract-hydra-count.svg)](https://www.npmjs.com/package/@comunica/actor-rdf-metadata-extract-hydra-count)

An [RDF Metadata Extract](https://github.com/comunica/comunica/tree/master/packages/bus-rdf-metadata-extract) actor that
extract estimated counts in the [Hydra Core vocabulary](https://www.hydra-cg.com/spec/latest/core/)
and [VoID](https://www.w3.org/TR/void/).

This module is part of the [Comunica framework](https://github.com/comunica/comunica),
and should only be used by [developers that want to build their own query engine](https://comunica.dev/docs/modify/).

[Click here if you just want to query with Comunica](https://comunica.dev/docs/query/).

## Install

```bash
$ yarn add @comunica/actor-rdf-metadata-extract-hydra-count
```

## Metadata entries

This actor adds the following entries to the metadata object.

* `cardinality`: Value of `http://www.w3.org/ns/hydra/core#totalItems` or `http://rdfs.org/ns/void#triples` represented as `{ type: 'exact' | 'estimate', value: number }`.

## Configure

After installing, this package can be added to your engine's configuration as follows:
```text
{
  "@context": [
    ...
    "https://linkedsoftwaredependencies.org/bundles/npm/@comunica/actor-rdf-metadata-extract-hydra-count/^5.0.0/components/context.jsonld"
  ],
  "actors": [
    ...
    {
      "@id": "urn:comunica:default:rdf-metadata-extract/actors#hydra-count",
      "@type": "ActorRdfMetadataExtractHydraCount",
      "predicates": [
        "http://www.w3.org/ns/hydra/core#totalItems",
        "http://rdfs.org/ns/void#triples"
      ]
    }
  ]
}
```

### Config Parameters

* `predicate`: The predicates to consider when determining counts, defaults to `http://www.w3.org/ns/hydra/core#totalItems` and `http://rdfs.org/ns/void#triples`.

---
_Source: https://npm.io/package/@comunica/actor-rdf-metadata-extract-hydra-count · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._