@comunica/actor-rdf-metadata-extract-hydra-pagesize

Comunica Hydra Pagesize RDF Metadata Extract Actor

An RDF Metadata Extract actor that extract page sizes in the Hydra Core vocabulary.

This module is part of the Comunica framework, and should only be used by developers that want to build their own query engine.

Click here if you just want to query with Comunica.

Install

$ yarn add @comunica/actor-rdf-metadata-extract-hydra-pagesize

Metadata entries

This actor adds the following entries to the metadata object.

• pageSize: Value of http://www.w3.org/ns/hydra/core#itemsPerPage.

Configure

After installing, this package can be added to your engine's configuration as follows:

{
  "@context": [
    ...
    "https://linkedsoftwaredependencies.org/bundles/npm/@comunica/actor-rdf-metadata-extract-hydra-pagesize/^4.0.0/components/context.jsonld"
  ],
  "actors": [
    ...
    {
      "@id": "urn:comunica:default:rdf-metadata-extract/actors#hydra-pagesize",
      "@type": "ActorRdfMetadataExtractHydraPagesize",
      "predicates": [
        "http://www.w3.org/ns/hydra/core#itemsPerPage"
      ]
    }
  ]
}

Config Parameters

• predicates: The predicates to consider when determining page size, defaults to http://www.w3.org/ns/hydra/core#itemsPerPage.

Changelog

v4.2.0 - 2025-04-29

Added

• Add HTTP rate limit actor
• Add workaround for DBPedia SPARQL HTTP status 405 with Retry-After
• Add VoID metadata extract actor and cardinality estimation for SPARQL sources
• Allow SPARQL source actor to skip COUNTs for large queries
• Allow sending COUNT queries to be disabled for SPARQL endpoints
• Allow forcing SPARQL source type from config
• Add join sorter based on join selectivities
• Report the url when a fetch fails
• Add distinctConstruct key to IQueryContextCommon

Changed

• Detect SPARQL endpoints with trailing slashes, Closes #1529
• Skip COUNT queries to singular SPARQL source
• Skip unnecessary SPARQL SD requests for a single source
• Update to rdf-streaming-store v2
• Try action.mediaType before doing heuristics for media type
• Avoid unnecessary parse attempts after dereferencing fails
• Avoid printing all metadata in join logging (#1509)
• Avoid creation of intermediary triple objects for in-memory stores

Fixed

• Fix variable names in ActorOptimizeQueryOperationPruneEmptySourceOperations
• Fix incorrect id of actor-query-source-hypermedia-identify-sparql
• Fix GraphQL queries being sent to SPARQL endpoints, Closes #1525
• Fix HTTP request count tracking, Closes #1526
• Fix bad plans sometimes being chosen due to requestTime in files
• Fix regressions of initialBindings with BIND clauses
• Fix queries with complex property paths not terminating
• Avoid flattening joins with input-specific metadata (#1522)
• Fix broken Dockerfile for query-sparql

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