This module was first released with Jena 2.11.0.

This extension to ARQ combines SPARQL and text search.

It gives applications the ability to perform free text searches within SPARQL queries. Text indexes are additional information for accessing the RDF graph.

The text index can be either Apache Lucene for a same-machine text index, or Apache Solr for a large scale enterprise search application.

Some example code is available here.

This module is not compatible with the much older LARQ module.


This query makes a text query for 'word' on a specific property (the index needs to correctly configured) and limits the output to 10 matches; it then looks in the RDF data for the actual label. More details are given below.

PREFIX text: <>
PREFIX rdfs: <>

{ ?s text:query (rdfs:label 'word' 10) ; 
     rdfs:label ?label 

Table of Contents


The text index is used provide a reverse index mapping query strings to URIs. The text indexed can be part of the RDF data or the text index can be used to index external content with only additional RDF in the RDF store.

The text index uses the native query language of the index: Lucene query format or Solr query format.

A text-supporting dataset is configured with a description of which properties work with. When data is added, any properties matching the description cause an entry to be added from analysed text from the triple object and mapping to the subject.

Pattern A – RDF data

In this pattern, the data in the text index is indexing literals in the RDF data.
Additions to the RDF data are reflected in additions to the index.

(Deletes do not remove text index entries - see below)

Pattern B – External content

There is no requirement that the text data indexed is present in the RDF data. As long as the index contains the index text documents to match the index description, then text search can be performed.

For example, if the content of a collection of documents is indexed and the URI naming the document is the result of the text search, then an RDF dataset with the document metadata can be combined with accessing the content by URI.

The maintenance of the index is external to the RDF data store.

External applications

By using Solr, in either pattern A (RDF data indexed) or pattern B (external content indexed), other applications can share the text index with SPARQL search.

Query with SPARQL

The property function is more conveniently written:

PREFIX text: <>

...   text:query ...

This is different to LARQ v1.

The following forms are all legal:

?s text:query 'word'                   # query
?s text:query (rdfs:label 'word')      # query specific property if multiple
?s text:query ('word' 10)              # with limit on results
(?s ?score) text:query 'word'          # query capturing also the score
(?s ?score ?literal) text:query 'word' # ... and original literal value

The most general form is:

 (?s ?score ?literal) text:query (property 'query string' 'limit')

Only the query string is required, and if it is the only argument the surrounding ( ) can be omitted.

The property URI is only necessary if multiple properties have been indexed.

 Argument    Definition 
property The URI (inc prefix name form)
query string The native query string
limit The limit on the results

Good practice

The query execution does not know the selectivity of the text index. It is better to use one of two styles.

Query pattern 1 – Find in the text index and enhance results

Access to the index is first in the query and used to find a number of items of interest; further information is obtained about these items from the RDF data.

{ ?s text:query (rdfs:label 'word' 10) ; 
     rdfs:label ?label ;
     rdf:type   ?type 

Limit is useful here when working with large indexes to limit results to the more higher scoring results.

Query pattern 2 – Filter

By finding items of interest first in the RDF data, the text search can be used to restrict the items found still further.

{ ?s rdf:type     :book ;
     dc:creator  "John" .
  ?s text:query   (dc:title 'word') ; 


The usual way to describe an index is with a Jena assembler description. Configurations can also be built with code. The assembler describes a 'text dataset' which has an underlying RDF dataset and a text index. The text index describes the text index technology (Lucene or Solr) and the details needed for for each.

A text index has an "entity map" which defines the properties to index, the name of the lucene/solr field and field used for storing the URI itself.

For common RDF use, there will be one field, mapping a property to a text index field. More complex setups, with multiple properties per entity (URI) are possible.

Once setup this way, any data added to the text dataset is automatically indexed as well.

Text Dataset Assembler

The following is an example of a TDB dataset with a text index.

@prefix :        <http://localhost/jena_example/#> .
@prefix rdf:     <> .
@prefix rdfs:    <> .
@prefix tdb:     <> .
@prefix ja:      <> .
@prefix text:    <> .

## Example of a TDB dataset and text index
## Initialize TDB
[] ja:loadClass "org.apache.jena.tdb.TDB" .
tdb:DatasetTDB  rdfs:subClassOf  ja:RDFDataset .
tdb:GraphTDB    rdfs:subClassOf  ja:Model .

## Initialize text query
[] ja:loadClass       "org.apache.jena.query.text.TextQuery" .
# A TextDataset is a regular dataset with a text index.
text:TextDataset      rdfs:subClassOf   ja:RDFDataset .
# Lucene index
text:TextIndexLucene  rdfs:subClassOf   text:TextIndex .
# Solr index
text:TextIndexSolr    rdfs:subClassOf   text:TextIndex .

## ---------------------------------------------------------------
## This URI must be fixed - it's used to assemble the text dataset.

:text_dataset rdf:type     text:TextDataset ;
    text:dataset   <#dataset> ;
    text:index     <#indexLucene> ;

# A TDB datset used for RDF storage
<#dataset> rdf:type      tdb:DatasetTDB ;
    tdb:location "DB" ;
    tdb:unionDefaultGraph true ; # Optional

# Text index description
<#indexLucene> a text:TextIndexLucene ;
    text:directory <file:Lucene> ;
    ##text:directory "mem" ;
    text:entityMap <#entMap> ;

# Mapping in the index
# URI stored in field "uri"
# rdfs:label is mapped to field "text"
<#entMap> a text:EntityMap ;
    text:entityField      "uri" ;
    text:defaultField     "text" ;
    text:map (
         [ text:field "text" ; text:predicate rdfs:label ]
         ) .

then use code such as:

Dataset ds = DatasetFactory.assemble(
    "http://localhost/jena_example/#text_dataset") ;

Key here is that the assembler contains two dataset definitions, one for the text dataset, one for the base data. Therefore, the application needs to identify the text dataset by it's URI http://localhost/jena_example/#text_dataset.

Configuring an Analyzer

Text to be indexed is passed through a text analyzer that divides it into tokens and may perform other transformations such as eliminating stop words. If a Solr text index is used, the analyzer used is determined by the Solr configuration. If a Lucene text index is used, then by default a StandardAnalyzer is used. However, it can be replaced by another analyzer with the text:analyzer property. For example with a SimpleAnalyzer:

<#indexLucene> a text:TextIndexLucene ;
        text:directory <file:Lucene> ;
        text:analyzer [
            a text:SimpleAnalyzer

It is possible to configure an alternative analyzer for each field indexed in a Lucene index. For example:

<#entMap> a text:EntityMap ;
    text:entityField      "uri" ;
    text:defaultField     "text" ;
    text:map (
         [ text:field "text" ; 
           text:predicate rdfs:label ;
           text:analyzer [
               a text:StandardAnalyzer ;
               text:stopWords ("a" "an" "and" "but")
         ) .

will configure the index to analyze values of the 'text' field using a StandardAnalyzer with the given list of stop words.

Other analyzer types that may be specified are SimpleAnalyzer and KeywordAnalyzer, neither of which has any configuration parameters. See the Lucene documentation for details of what these analyzers do. Jena also provides LowerCaseKeywordAnalyzer, which is a case-insensitive version of KeywordAnalyzer, and ConfigurableAnalyzer (see below).

Support for the new LocalizedAnalyzer has been introduced in Jena 3.0.0 to deal with Lucene language specific analyzers. See Linguistic Support with Lucene Index part for details.


ConfigurableAnalyzer was introduced in Jena 3.0.1. It allows more detailed configuration of text analysis parameters by independently selecting a Tokenizer and zero or more TokenFilters which are applied in order after tokenization. See the Lucene documentation for details on what each tokenizer and token filter does.

The available Tokenizer implementations are:

  • StandardTokenizer
  • KeywordTokenizer
  • WhitespaceTokenizer
  • LetterTokenizer

The available TokenFilter implementations are:

  • StandardFilter
  • LowerCaseFilter
  • ASCIIFoldingFilter

Configuration is done using Jena assembler like this:

text:analyzer [
  a text:ConfigurableAnalyzer ;
  text:tokenizer text:KeywordTokenizer ;
  text:filters (text:ASCIIFoldingFilter, text:LowerCaseFilter)

Here, text:tokenizer must be one of the four tokenizers listed above and the optional text:filters property specifies a list of token filters.

Analyzer for Query

New in Jena 2.13.0.

There is an ability to specify an analyzer to be used for the query string itself. It will find terms in the query text. If not set, then the analyzer used for the document will be used. The query analyzer is specified on the TextIndexLucene resource:

<#indexLucene> a text:TextIndexLucene ;
    text:directory <file:Lucene> ;
    text:entityMap <#entMap> ;
    text:queryAnalyzer [
        a text:KeywordAnalyzer

Alternative Query Parsers

New in Jena 3.1.0.

It is possible to select another query parser (currently only AnalyzingQueryParser is supported) instead of the default QueryParser. The main difference between these query parsers is that AnalyzingQueryParser performs analysis also for wildcard queries. This is useful in combination with accent-insensitive wildcard queries. The query parser is specified on the TextIndexLucene resource:

<#indexLucene> a text:TextIndexLucene ;
    text:directory <file:Lucene> ;
    text:entityMap <#entMap> ;
    text:queryParser text:AnalyzingQueryParser .

Configuration by Code

A text dataset can also be constructed in code as might be done for a purely in-memory setup:

    // Example of building a text dataset with code.
    // Example is in-memory.
    // Base dataset
    Dataset ds1 = DatasetFactory.createMem() ;

    EntityDefinition entDef = new EntityDefinition("uri", "text", RDFS.label) ;

    // Lucene, in memory.
    Directory dir =  new RAMDirectory();

    // Join together into a dataset
    Dataset ds = TextDatasetFactory.createLucene(ds1, dir, entDef) ;

Graph-specific Indexing

Starting with version 1.0.1, jena-text supports storing information about the source graph into the text index. This allows for more efficient text queries when the query targets only a single named graph. Without graph-specific indexing, text queries do not distinguish named graphs and will always return results from all graphs.

Support for graph-specific indexing is enabled by defining the name of the index field to use for storing the graph identifier.

If you use an assembler configuration, set the graph field using the text:graphField property on the EntityMap, e.g.

# Mapping in the index
# URI stored in field "uri"
# Graph stored in field "graph"
# rdfs:label is mapped to field "text"
<#entMap> a text:EntityMap ;
    text:entityField      "uri" ;
    text:graphField       "graph" ;
    text:defaultField     "text" ;
    text:map (
         [ text:field "text" ; text:predicate rdfs:label ]
         ) .

If you configure the index in Java code, you need to use one of the EntityDefinition constructors that support the graphField parameter, e.g.

    EntityDefinition entDef = new EntityDefinition("uri", "text", "graph", RDFS.label.asNode()) ;

Note: If you migrate from a global (non-graph-aware) index to a graph-aware index, you need to rebuild the index to ensure that the graph information is stored.

Linguistic support with Lucene index

It is now possible to take advantage of languages of triple literals to enhance index and queries. Sub-sections below detail different settings with the index, and use cases with SPARQL queries.

Explicit Language Field in the Index

Literals' languages of triples can be stored (during triple addition phase) into the index to extend query capabilities. For that, the new text:langField property must be set in the EntityMap assembler :

<#entMap> a text:EntityMap ;
    text:entityField      "uri" ;
    text:defaultField     "text" ;        
    text:langField        "lang" ;       

If you configure the index via Java code, you need to set this parameter to the EntityDefinition instance, e.g.

EntityDefinition docDef = new EntityDefinition(entityField, defaultField);

SPARQL Linguistic Clause Forms

Once the langField is set, you can use it directly inside SPARQL queries, for that the 'lang:xx' argument allows you to target specific localized values. For example:

//target english literals
?s text:query (rdfs:label 'word' 'lang:en' )

//target unlocalized literals
?s text:query (rdfs:label 'word' 'lang:none')

//ignore language field
?s text:query (rdfs:label 'word')


You can specify and use a LocalizedAnalyzer in order to benefit from Lucene language specific analyzers (stemming, stop words,...). Like any others analyzers, it can be done for default text indexation, for each different field or for query.

With an assembler configuration, the text:language property needs to be provided, e.g :

<#indexLucene> a text:TextIndexLucene ;
    text:directory <file:Lucene> ;
    text:entityMap <#entMap> ;
    text:analyzer [
        a text:LocalizedAnalyzer ;
        text:language "fr"

will configure the index to analyze values of the 'text' field using a FrenchAnalyzer.

To configure the same example via Java code, you need to provide the analyzer to the index configuration object:

    TextIndexConfig config = new TextIndexConfig(def);
    Analyzer analyzer = Util.getLocalizedAnalyzer("fr");
    Dataset ds = TextDatasetFactory.createLucene(ds1, dir, config) ;

Where def, ds1 and dir are instances of EntityDefinition, Dataset and Directory classes.

Note: You do not have to set the text:langField property with a single localized analyzer.

Multilingual Support

Let us suppose that we have many triples with many localized literals in many different languages. It is possible to take all this languages into account for future mixed localized queries. Just set the text:multilingualSupport property at true to automatically enable the localized indexation (and also the localized analyzer for query) :

<#indexLucene> a text:TextIndexLucene ;
    text:directory "mem" ;
    text:multilingualSupport true;     

Via Java code, set the multilingual support flag :

    TextIndexConfig config = new TextIndexConfig(def);
    Dataset ds = TextDatasetFactory.createLucene(ds1, dir, config) ;

Thus, this multilingual index combines dynamically all localized analyzers of existing languages and the storage of langField properties.

For example, it is possible to involve different languages into the same text search query :

    { ?s text:query ( rdfs:label 'institut' 'lang:fr' ) }
    { ?s text:query ( rdfs:label 'institute' 'lang:en' ) }

Hence, the result set of the query will contain "institute" related subjects (institution, institutional,...) in French and in English.

Note: If the text:langField property is not set, the "lang" field will be used anyway by default, because multilingual index cannot work without it.

Storing Literal Values

New in Jena 3.0.0.

It is possible to configure the text index to store enough information in the text index to be able to access the original indexed literal values at query time. This is controlled by two configuration options. First, the text:storeValues property must be set to true for the text index:

<#indexLucene> a text:TextIndexLucene ;
    text:directory "mem" ;
    text:storeValues true;     

Or using Java code, used the setValueStored method of TextIndexConfig:

    TextIndexConfig config = new TextIndexConfig(def);

Additionally, setting the langField configuration option is recommended. See Linguistic Support with Lucene Index for details. Without the langField setting, the stored literals will not have language tag or datatype information.

At query time, the stored literals can be accessed by using a 3-element list of variables as the subject of the text:query property function. The literal value will be bound to the third variable:

(?s ?score ?literal) text:query 'word'

Working with Fuseki

The Fuseki configuration simply points to the text dataset as the fuseki:dataset of the service.

<#service_text_tdb> rdf:type fuseki:Service ;
    rdfs:label                      "TDB/text service" ;
    fuseki:name                     "ds" ;
    fuseki:serviceQuery             "query" ;
    fuseki:serviceQuery             "sparql" ;
    fuseki:serviceUpdate            "update" ;
    fuseki:serviceUpload            "upload" ;
    fuseki:serviceReadGraphStore    "get" ;
    fuseki:serviceReadWriteGraphStore    "data" ;
    fuseki:dataset                  :text_dataset ;

Building a Text Index

When working at scale, or when preparing a published, read-only, SPARQL service, creating the index by loading the text dataset is impractical.
The index and the dataset can be built using command line tools in two steps: first load the RDF data, second create an index from the existing RDF dataset.

Step 1 - Building a TDB dataset

Note: If you have an existing TDB dataset then you can skip this step

Build the TDB dataset:

java -cp $FUSEKI_HOME/fuseki-server.jar tdb.tdbloader --tdb=assembler_file data_file

using the copy of TDB included with Fuseki.

Alternatively, use one of the TDB utilities tdbloader or tdbloader2 which are better for bulk loading:

$JENA_HOME/bin/tdbloader --loc=directory  data_file

Step 2 - Build the Text Index

You can then build the text index with the jena.textindexer tool:

java -cp $FUSEKI_HOME/fuseki-server.jar jena.textindexer --desc=assembler_file

Because a Fuseki assembler description can have several datasets descriptions, and several text indexes, it may be necessary to extract a single dataset and index description into a separate assembler file for use in loading.

Updating the index

If you allow updates to the dataset through Fuseki, the configured index will automatically be updated on every modification. This means that you do not have to run the above mentioned jena.textindexer after updates, only when you want to rebuild the index from scratch.

Deletion of Indexed Entities

If the text index is being maintain by changed to the RDF, then deletion of RDF triple or quads does not cause entries in the index to be removed. The index does not store the literal indexed, nor does it store a reference count of how many triples refer to the index so the information to delete entries is not available.

In situations where this matters, the SPARQL query should look up in the text index, then check in the RDF data. Indeed, this may be necessary anyway because a text search does not necessarily give only exact matches.

In the initial example:

SELECT ?s ?label
{ ?s text:query (rdfs:label 'word' 10) ; 
     rdfs:label ?label 

the SPARQL query is checking that the rdfs:label triple exists, and if it does, returning the whole label.

Jena 3.0 provides a solution to address this situation. RDF triple deletion can be synchronized within the index. Each removed triple literals in the graph can automatically have their related entry removed in the index. A unique ID is computed, and stored in the index, to represent the quad. It guarantees the uniqueness of the stored information and allows to retrieve it easily.

To enable Deletion support, this uid field must be provided within the configuration.

If you use an assembler configuration, set the uid field using the text:uidField property on the EntityMap, e.g.

<#entMap> a text:EntityMap ;
    text:entityField      "uri" ;
    text:defaultField     "text" ;        
    text:uidField         "uid" ;       

If you configure the index via Java code, you need to set this parameter to the EntityDefinition instance, e.g.

EntityDefinition docDef = new EntityDefinition(entityField, defaultField);

Note: If you migrate from a global (non-deletion-support) index to a deletion-support index, you need to rebuild the index to ensure that the uid information is stored.

Configuring Alternative TextDocProducers

The default behaviour when text indexing is to index a single property as a single field, generating a different Document for each indexed triple. To change this behaviour requires writing and configuring an alternative TextDocProducer.

To configure a TextDocProducer, say net.code.MyProducer in a dataset assembly, use the property textDocProducer, eg:

<#ds-with-lucene> rdf:type text:TextDataset;
    text:index <#indexLucene> ;
    text:dataset <#ds> ;
    text:textDocProducer <java:net.code.MyProducer> ;

where CLASSNAME is the full java class name. It must have either a single-argument constructor of type TextIndex, or a two-argument constructor (DatasetGraph, TextIndex). The TextIndex argument will be the configured text index, and the DatasetGraph argument will be the graph of the configured dataset.

For example, to explicitly create the default TextDocProducer use:

    text:textDocProducer <java:org.apache.jena.query.text.TextDocProducerTriples> ;

TextDocProducerTriples produces a new document for each subject/field added to the dataset, using TextIndex.addEntity(Entity).


The example class below is a TextDocProducer that only indexes ADDs of quads for which the subject already had at least one property-value. It uses the two-argument constructor to give it access to the dataset so that it count the (?G, S, P, ?O) quads with that subject and predicate, and delegates the indexing to TextDocProducerTriples if there are at least two values for that property (one of those values, of course, is the one that gives rise to this change()).

  public class Example extends TextDocProducerTriples {

      final DatasetGraph dg;

      public Example(DatasetGraph dg, TextIndex indexer) {
          this.dg = dg;

      public void change(QuadAction qaction, Node g, Node s, Node p, Node o) {
          if (qaction == QuadAction.ADD) {
              if (alreadyHasOne(s, p)) super.change(qaction, g, s, p, o);

      private boolean alreadyHasOne(Node s, Node p) {
          int count = 0;
          Iterator<Quad> quads = dg.find( null, s, p, null );
          while (quads.hasNext()) {; count += 1; }
          return count > 1;

Maven Dependency

The jena-text module is included in Fuseki. To use it within application code, then use the following maven dependency:


adjusting the version X.Y.Z as necessary. This will automatically include a compatible version of Lucene and the Solr java client, but not Solr server.