Connectors

The GraphDB Connectors provide extremely fast keyword and faceted (aggregation) searches that are typically implemented by an external component or service, but have the additional benefit of staying automatically up-to-date with the GraphDB repository data.

The Connectors provide synchronisation at the entity level, where an entity is defined as having a unique identifier (URI) and a set of properties and property values. In terms of RDF, this corresponds to a set of triples that have the same subject. In addition to simple properties (defined by a single triple), the Connectors support property chains. A property chain is defined as a sequence of triples where each triple’s object is the subject of the subsequent triple.

GraphDB EE comes with the following connector implementations:

Features Comparison Table:

Feature Lucene Solr Elasticsearch
FTS search ✅ ✅ ✅
Simple facets ✅ ✅ ✅
Sorting ✅ ✅ ✅
Snippet extraction ✅ ✅ ✅
Limit and offset ✅ ✅ ✅
Fixed range facets ❌ ✅ ✅
Variable range facets ❌ ✅ ✅
Nested facets ❌ ✅ ✅

Aggregations

  • terms
  • histogram
  • range
  • min/max
  • sum
  • average
  • count
  • standard deviation
  • variance
  • sum of squares
 ❌ ❌ ✅
Sub-aggregations ❌ ❌ ✅