Your exception is thrown because you've got a '*' as the first
character of your query. By default the lucene query parser doesn't
allow this, but you can override that by a call to
QueryParser#setAllowLeadingWildcard(boolean). How you would do that in
your setting I don't know, though.
Den tisdag 21 december 2010 skrev Schmidt, Dennis<dennis.schm...@sap.com>:
> Hi all,
>
> I am currently using the LuceneSail on top of a
> DirectTypeHierarchyInferencer, ForwardChainingRDFSInferencer and a
> MemoryStore.
> When using the following query, the LuceSail is obviously already working
> somehow, since the queries are roughly twice as fast as before. Still not the
> real performance gain I was expecting from using Lucene (side note: the
> Strings are in fact only short text snippets of usually no more than 30
> characters).
> ----
> SELECT entity, name, type
> FROM {entity} rdfs:label {name} rdf:type {type}
> WHERE name LIKE "*search this*" IGNORE CASE
> ----
> The LuceneSail homepage
> (http://dev.nepomuk.semanticdesktop.org/wiki/LuceneSail) introduces a
> different query format for using LuceneSail, so I was using this instead to
> see what happens. I changed the query to look like this then:
> ----
> PREFIX search:<http://www.openrdf.org/contrib/lucenesail#>
> SELECT ?entity ?name ?type WHERE {
> ?entity search:matches ?match ;
> rdf:type ?type .
> ?match search:query "*search this*" . }
> ----
> I only changed from SERQL to SPARQL because SPARQL was used in the example as
> well. With this, the query is being executed correctly (meaning no Exceptions
> or anything) but then, there are never any results returned and the query
> execution is blazingly fast (which leads me to the conclusion it is in fact
> not executed as expected).
>
> So am I missing something there or what might be the reason? Another to me
> unexpected behaviour is that, when using a wildcard character at the
> beginning of a search string, I get the following error message. Why can I
> not use a wildcard at the beginning here? Doesn't make any sense to me.
> ----
> org.openrdf.sail.lucene.LuceneQueryIterator - There was a problem evaluating
> query '*search this*' for property 'null!
> org.apache.lucene.queryParser.ParseException: Cannot parse '*search this*':
> '*' or '?' not allowed as first character in WildcardQuery
> ----
>
> Thanks a lot in advance,
> Dennis
>
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