/**
* Return the class partition statistics for the named graph.
*
* @param kb The KB instance.
* @param civ The {@link IV} of a named graph (required).
* @return The class partition statistics for that named graph. Only class partitions which are
* non-empty are returned.
*/
protected static IVCount[] classUsage(
final AbstractTripleStore kb, final IV<?, ?> civ, final IVCount[] classPartitionCounts) {
final SPORelation r = kb.getSPORelation();
final boolean quads = kb.isQuads();
if (!quads) {
// Named graph only valid in quads mode.
throw new IllegalArgumentException();
}
// Resolve IV for rdf:type
final BigdataURI rdfType = kb.getValueFactory().asValue(RDF.TYPE);
kb.getLexiconRelation()
.addTerms(new BigdataValue[] {rdfType}, 1 /* numTerms */, true /* readOnly */);
if (rdfType.getIV() == null) {
// No rdf:type assertions since rdf:type is unknown term.
return new IVCount[0];
}
// The non-zero counts.
final List<IVCount> counts = new LinkedList<IVCount>();
// Check the known non-empty predicate partitions.
for (IVCount in : classPartitionCounts) {
final long n =
r.getAccessPath(null, rdfType.getIV() /* p */, in.iv /* o */, civ)
.rangeCount(false /* exact */);
if (n == 0) continue;
final IVCount out = new IVCount(in.iv, n);
out.setValue(in.getValue());
counts.add(out);
}
final IVCount[] a = counts.toArray(new IVCount[counts.size()]);
// Order by descending count.
Arrays.sort(a);
return a;
}
/**
* Return an efficient statistical summary for the class partitions. The SPARQL query for this is
*
* <pre>
* SELECT ?class (COUNT(?s) AS ?count ) { ?s a ?class } GROUP BY ?class ORDER BY ?count
* </pre>
*
* However, it is much efficient to scan POS for
*
* <pre>
* rdf:type ?o ?s
* </pre>
*
* and report the range count of
*
* <pre>
* rdf:type ?o ?s
* </pre>
*
* for each distinct value of <code>?o</code>.
*
* @param kb The KB instance.
* @return The class usage statistics.
*/
protected static IVCount[] classUsage(final AbstractTripleStore kb) {
final SPORelation r = kb.getSPORelation();
if (r.oneAccessPath) {
// The necessary index (POS or POCS) does not exist.
throw new UnsupportedOperationException();
}
final boolean quads = kb.isQuads();
final SPOKeyOrder keyOrder = quads ? SPOKeyOrder.POCS : SPOKeyOrder.POS;
// Resolve IV for rdf:type
final BigdataURI rdfType = kb.getValueFactory().asValue(RDF.TYPE);
kb.getLexiconRelation()
.addTerms(new BigdataValue[] {rdfType}, 1 /* numTerms */, true /* readOnly */);
if (rdfType.getIV() == null) {
// No rdf:type assertions since rdf:type is unknown term.
return new IVCount[0];
}
// visit distinct term identifiers for the rdf:type predicate.
@SuppressWarnings("rawtypes")
final IChunkedIterator<IV> itr =
r.distinctMultiTermScan(keyOrder, new IV[] {rdfType.getIV()} /* knownTerms */);
// resolve term identifiers to terms efficiently during iteration.
final BigdataValueIterator itr2 = new BigdataValueIteratorImpl(kb /* resolveTerms */, itr);
try {
final Set<IV<?, ?>> ivs = new LinkedHashSet<IV<?, ?>>();
final Map<IV<?, ?>, IVCount> counts = new LinkedHashMap<IV<?, ?>, IVCount>();
while (itr2.hasNext()) {
final BigdataValue term = itr2.next();
final IV<?, ?> iv = term.getIV();
final long n =
r.getAccessPath(null, rdfType.getIV() /* p */, iv /* o */, null)
.rangeCount(false /* exact */);
ivs.add(iv);
counts.put(iv, new IVCount(iv, n));
}
// Batch resolve IVs to Values
final Map<IV<?, ?>, BigdataValue> x = kb.getLexiconRelation().getTerms(ivs);
for (Map.Entry<IV<?, ?>, BigdataValue> e : x.entrySet()) {
final IVCount count = counts.get(e.getKey());
count.setValue(e.getValue());
}
final IVCount[] a = counts.values().toArray(new IVCount[counts.size()]);
// Order by descending count.
Arrays.sort(a);
return a;
} finally {
itr2.close();
}
}