Module sparql-view-unfold

Fileoverview

View unfolding and query optimisation for SPARQL 1.2.

Rewrites a SPARQL 1.2 query posed over views into an equivalent query over the data those views are defined on.

A mapping is one or more SPARQL CONSTRUCT queries defining a view: the template (head) says which triples the view holds, the WHERE clause (body) how they are found in the data. A pipeline of transformations is then run over the user query, the first of which unfolds that mapping into every triple pattern and the rest of which optimise what comes out.

Running SPARQL 1.2 queries - triple terms and all - against RDF 1.1 data is the case this was built for: a view then says how RDF 1.1 data represents RDF 1.2, and the rewrite hands back plain SPARQL 1.1.

This entry point is platform-neutral, and is kept that way deliberately: the one transformation needing a Comunica runtime is reached through the sparql-view-unfold/comunica subpath instead, because re-exporting it here would put node:module and node:path in every consumer's module graph. See the Comunica entry point for why a bundler cannot shake that back out.

See

https://w3c.github.io/rdf-interop/spec/ RDF 1.2 Interoperability Spec

Example

import {
  createQueryRewriter,
  filterFalseTransformation,
  mappingFromConstructQueries,
  unfoldingTransformation,
} from 'sparql-view-unfold';

const rewriter = createQueryRewriter([
  unfoldingTransformation(mappingFromConstructQueries([
    'CONSTRUCT { ?t rdf:reifies <<( ?s ?p ?o )>> } WHERE { ... RDF 1.1 pattern ... }',
  ])),
  filterFalseTransformation(),
]);
const sparql11Query = await rewriter.rewriteQuery('SELECT * WHERE { ?x rdf:reifies <<( ?s ?p ?o )>> }');

References

createDefaultTransformationPipeline → createDefaultTransformationPipeline
createQueryRewriter → createQueryRewriter
DT_INTERNAL_BNODE → DT_INTERNAL_BNODE
extendsToValuesTransformation → extendsToValuesTransformation
EXTENSION_FUNCTION_BNODE → EXTENSION_FUNCTION_BNODE
filterFalseTransformation → filterFalseTransformation
internalBnodeAsSpecialIriTransformation → internalBnodeAsSpecialIriTransformation
internalBnodeAsSpecialLiteralTransformation → internalBnodeAsSpecialLiteralTransformation
IRI_PREFIX_BNODE → IRI_PREFIX_BNODE
joinValuesToFilterTransformation → joinValuesToFilterTransformation
Mapping → Mapping
mappingFromConstructQueries → mappingFromConstructQueries
MappingHead → MappingHead
MappingOptions → MappingOptions
nullifyJoinOverIncompatibleBoundsTransformation → nullifyJoinOverIncompatibleBoundsTransformation
nullifyUnbindableVarsTransformation → nullifyUnbindableVarsTransformation
pullUpExtendsTransformation → pullUpExtendsTransformation
pushDownAssertionsTransformation → pushDownAssertionsTransformation
QueryRewriter → QueryRewriter
QueryTransformation → QueryTransformation
removeProjectionsTransformation → removeProjectionsTransformation
rewriteNonRecursivePathsTransformation → rewriteNonRecursivePathsTransformation
serviceCallPushUpTransformation → serviceCallPushUpTransformation
TransformationContext → TransformationContext
UnfoldingOptions → UnfoldingOptions
unfoldingTransformation → unfoldingTransformation
VAR_PREFIX_MAPPING → VAR_PREFIX_MAPPING
VAR_PREFIX_MERGED_HEAD → VAR_PREFIX_MERGED_HEAD
VAR_PREFIX_USER_QUERY → VAR_PREFIX_USER_QUERY

Module sparql-view-unfold

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See

Example

References

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