@comunica/bus-query-operation

Comunica Bus Query Operation

A bus for evaluating SPARQL algebra operations.

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/bus-query-operation

Bus usage

• Context: "https://linkedsoftwaredependencies.org/bundles/npm/@comunica/bus-query-operation/^4.0.0/components/context.jsonld"
• Bus name: ActorQueryOperation:_default_bus

Creating actors on this bus

Actors extending ActorQueryOperation or ActorQueryOperationTyped are automatically subscribed to this bus.

It is recommended to extend from ActorQueryOperationTyped if your actor supports a single query operation, as the bus will be able to handle this actor more efficiently. This is not applicable if your actor handles multiple different types of query operations.

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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