Question

I’m using Hibernate Search (which uses Lucene) for searching some Data I have indexed in a directory. It works fine but I need to do a reverse search. By reverse search I mean that I have a list of queries stored in my database I need to check which one of these queries match with a Data object each time Data Object is created. I need it to alert the user when a Data Object matches with a Query he has created. So I need to index this single Data Object which has just been created and see which queries of my list has this object as a result.

I’ve seen Lucene MemoryIndex Class to create an index in memory so I can do something like this example for every query in a list (though iterating in a Java list of queries would not be very efficient):

//Iterating over my list<Query>
MemoryIndex index = new MemoryIndex();
//Add all fields
index.addField("myField", "myFieldData", analyzer);
...
QueryParser parser = new QueryParser("myField", analyzer);
float score = index.search(query);
if (score > 0.0f) {
    System.out.println("it's a match");
} else {
    System.out.println("no match found");
}

The problem here is that this Data Class has several Hibernate Search Annotations @Field,@IndexedEmbedded,… which indicated how fields should be indexed, so when I invoke index() method on the FullTextEntityManager instance it uses this information to index the object in the directory. Is there a similar way to index it in memory using this information?

Is there a more efficient way of doing this reverse search?

Answer 1

Just index the new object (if you use automatic indexing you don’t have to do anything besides committing the current transaction), then retrieve the queries you want to run and run all of them in a boolean query, combining the stored query with the id of the new object. Something like this:

...
BooleanQuery query = new BooleanQuery();
query.add(storedQuery, BooleanClause.Occur.MUST);
query.add(new TermQuery(ProjectionConstants.ID, id), BooleanClause.Occur.MUST);
... 

If you get a result you know the query matched.