Barry Bishop
Mon, 14 Jun 2010 16:26:44 -0700
Hi Yonghong, The message is telling you that Lucene search can not be used until the Lucene index has been built. The following extract from the soon-to-released user guide should help: 4.4.2 RDF Search - Full-Text Search using Lucene Lucene In order to use Lucene integration in BigOWLIM the Lucene indices must first be computed. During this process, for each node in the repository its surrounding molecule is computed. Then each such molecule is converted into a single string document (by concatenating the textual representation of all the nodes in the molecule) and this document is indexed by Lucene. If RDF Rank is available in the repository for this node (see section is a high-performance, full-featured text search engine library written entirely in Java. Beginning with BigOWLIM version 3.2, full text search capabilities using the Lucene engine are supported. The preliminary version of Lucene integration supports indexing and query evaluation over the entire repository, i.e. all nodes including both URI local names and literals. 8.1), it is stored in Lucene's index as a boosting factor that will later on influence the selection order. This combination of ranking RDF molecules (discussed later in section 8.1) together with full-text search provides a powerful mechanism for querying/analysing datasets even when the schema is not known. This allows for keyword-based search over both literals and URIs with the results ordered by importance/interconnectedness. For an example of this kind of ‘RDF Search’, see the Linked Data Semantic Repository2 The Lucene index can be generated by running a command line utility distributed with BigOWLIM's jar file: java -DrepositoryPath=<path> com.ontotext.trree.GenerateLuceneIndex Note: In the current release, this cannot be achieved via the Sesame API and access to the local repository is required. After the index is built the user is able to run RDF Search queries by utilising a special system predicate in a SPARQL query, e.g. PREFIX gossip:<http://www.ontotext.com/rascalli/2008/04/gossipdb.owl#> PREFIX onto: <http://www.ontotext.com/> SELECT * WHERE { ?person gossip:name ?name . ?name onto:luceneQuery "American AND life~" . } If the Lucene index has not been built, there will be no matches for triple patterns using the onto:luceneQuery system predicate. The object of this triple pattern is a literal containing the Lucene query conforming to the syntax described here: http://lucene.apache.org/java/3_0_0/queryparsersyntax.html The ?name subject variable is then bound to all nodes in the repository whose surrounding molecule matches the Lucene query. The order of the results is heavily influenced by the node’s RDF rank, if it was available during the indexing process. In the future, we are planning to allow the creation of the lucene index using a special ASK query. However, this will not be completed for at least a few weeks. I hope this helps, barry PS I cc'ed the owlim-discussion mailing list, as this is more appropriate for this kind of question. On 14/06/2010 17:07, yonghong ke wrote: > Hi: > I am using bigowl 3.2.a7, when i run the wordnet example, i got a error: > ERROR [com.ontotext.trree.d.b] - Failed opening Lucene indexes. Lucene > search won't be available. > > how to fix it? thanks very much! > > > > > _______________________________________________ > Interested-in-OWLIM mailing list > interested-in-ow...@ontotext.com > http://ontotext.com/mailman/listinfo/interested-in-owlim _______________________________________________ OWLIM-discussion mailing list OWLIM-discussion@ontotext.com http://ontotext.com/mailman/listinfo/owlim-discussion