@comunica/mediator-number

Comunica Number Mediator

A mediator that can mediate over a single number field. It can either choose the actor with the maximum or with the minimum value.

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/mediator-number

Configure

After installing, this mediator can be instantiated as follows:

{
  "@context": [
    ...
    "https://linkedsoftwaredependencies.org/bundles/npm/@comunica/mediator-number/^4.0.0/components/context.jsonld"
  ],
  "actors": [
    ...
    {
      "@type": "SomeActor",
      "someMediator": {
        "@id": "#mediatorQueryOperation",
        "@type": "MediatorNumber",
        "field": "httpRequests",
        "type": "min",
        "ignoreErrors": true,
        "bus": { "@id": "ActorQueryOperation:_default_bus" }
      }
    }
  ]
}

Instead of MediatorNumberMin, MediatorNumberMax could also be used to resolve to the maximum value.

Config Parameters

• bus: Identifier of the bus to mediate over.
• field: The field name to mediate over.
• type: The way how the index should be selected. For choosing the minimum value: 'min'. For choosing the maximum value: 'max'.
• ignoreErrors: Optional flag to indicate if actors that throw test errors should be ignored, defaults to false.

Changelog

v4.0.1 - 2024-10-15

BREAKING CHANGES

The following breaking changes will only impact users of Node.js < 18 and users that develop custom components or engines with Comunica.

• Remove backwards-compat for Node.js < 18
  • Remove cross-fetch and abort-controller polyfill as unnecessary
  • Update fetch-sparql-endpoint to version 5
  • Remove Node 14 backwards-compat in stats writer
• API changes
  • Refactor Actor.test to not rely on Promise rejections
    • All Actor.test methods must be changed to use passTest or failTest instead of promise rejections, for better performance.
  • Use variable.canBeUndef in metadata instead of canContainUndefs
  • Remove Actor.initialize and .deinitalize
  • Rename noCache CLI argument to invalidateCache
  • Remove hash collisions flag from hash buses
  • Return 32-bit numbers in hash bus based on specific variables
  • Allow inserts and deletes to execute in a single request
• Renamed or changed actors
  • Split expression functions into separate actors on dedicated bus
  • Split aggregators into separate actors on dedicated bus
  • Refactor HTTP fetch and retry logic
    • Retries of failed requests has been improved
    • The User-Agent header has been improved
    • A better approach to detect if Comunica is in a browser environment, compatible with Node.js, Deno, and Bun.
  • Remove SHA1 hash quads actor in favor of Murmur3
  • Remove SHA1 hash actor in favor of Murmur3
  • Abstract actor-rdf-join-minus-hash-undef into actor-rdf-join-minus-hash
• Move utilities
  • Add utils-query-operation and utils-iterator
    • These new packages contain helper functions that previously existed in bus-query-operation and bus-rdf-join.
  • Rename util packages to 'util-' scope
    • data-factory -> utils-data-factory
    • bindings-factory -> utils-bindings-factory
    • jest -> utils-jest
    • metadata -> utils-metadata
  • Move ActorRdfJoin.hashNonClashing to bindingsToCompactString
  • Delegate all join hashing to hash bus
  • Move bindings index from optional join to utils package

Added

• Add default Accept-Encoding header with Brotli
• Add undef support to inner hash join actor
• Forward side data from test to run in actors
• Allow plugging in custom DataFactory through context, Closes #358

Changed

• Remove unneeded false default values on CLI boolean args
• Improve fragment selector shape handling
  • Make doesShapeAcceptOperation recurse into operations
  • Add dedicated wildcard operation type to FragmentSelectorShape
• Improve performance
  • Bump asyncjoin with hash join performance improvement
  • Only consider overlapping vars when testing undef in join actors
• Improve type inference in IActionContext, Closes #933
• Emit planning time from stats writer
• Make stats writer measure time from actual query start
• Improve error reporting when mediators fail

Fixed

• Fix union not setting canContainUndefs to true if child vars differ

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