Comunica Statistic Intermediate Results

A statistics tracker package for tracking intermediate results produced during query execution in Comunica. This class must be added to the context with the key defined in the class.

This module is part of the Comunica framework,

Click here if you just want to query with Comunica.

Install

$ yarn add @comunica/statistic-intermediate-results
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Using the tracker

Adding the tracker to the context

    // Import the tracker
    import { StatisticIntermediateResults } from '@comunica/statistic-intermediate-results';

    // Create the Comunica engine
    const QueryEngine = require('@comunica/query-sparql').QueryEngine;
    const myEngine = new QueryEngine();
    const statisticTracker = new StatisticIntermediateResults();

    // Set up an event listener to handle data emitted by the tracker
    statisticTracker.on((intermediateResult) => console.log(intermediateResult));

    // Create a context object with the data source and add the tracker
    let context = {sources: ['https://fragments.dbpedia.org/2015/en']};
    context[statisticTracker.key.name] = statisticTracker;

    // Execute a SPARQL query using the engine with the configured context
    const bindingsStream = await myEngine.queryBindings(`
    SELECT ?s ?p ?o WHERE {
        ?s ?p ?o
    } LIMIT 10`, context);

    // Process the query results, as this runs intermediate results will be
    // logged
    bindingsStream.on('data', (binding) => {
        console.log(binding.toString());
    });
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Allowing Comunica to call the tracker

Comunica does not call the updateStatistic function by default. To enable this functionality, users should add the following actors to their Comunica configuration:

1. actor-query-operation-wrap-stream: This actor wraps query operation streams.
2. actor-rdf-join-wrap-stream: This actor wraps RDF join streams.

These actors ensure that the bus-iterator-transform is called for each intermediate iterator produced by Comunica.

3. actor-iterator-transform-record-intermediate-results: This actor is responsible for calling the updateStatistic method of statistic-intermediate-result for each produced intermediate result.

By adding these actors to your configuration, you enable Comunica to track and record intermediate results during query execution.