Hello,
I'm writing a small function to enumerate all the values of a field. I
decided that I'd base my code of the PrefixQuery.rewrite() code. This
code, as I understand it, is designed to expand a prefix wildcard and
rewrite the query as a long boolean series of ANDs.
To improve performance the code has a Break statement designed to kick
out of the TermEnum starts enumerating on another field.
//FROM /src/java/org/apache/lucene/search/PrefixQuery.java
public Query rewrite(IndexReader reader) throws IOException {
BooleanQuery query = new BooleanQuery(true);
TermEnum enumerator = reader.terms(prefix);
try {
String prefixText = prefix.text();
String prefixField = prefix.field();
do {
Term term = enumerator.term();
if (term != null &&
term.text().startsWith(prefixText) &&
term.field() == prefixField) // interned comparison
{
TermQuery tq = new TermQuery(term); // found a match
tq.setBoost(getBoost()); // set the boost
query.add(tq, BooleanClause.Occur.SHOULD); // add
to query
//System.out.println("added " + term);
} else {
break;
}
} while (enumerator.next());
} finally {
enumerator.close();
}
return query;
}
I think that there may be a logic problem here - - - to me it seems that
if I performed a prefix query on a Field that wasn't first in line
during the the TermEnum's output that my prefix would never be expanded.
I may be misunderstanding the ordering that IndexReader.terms(Term)
produces.
This seems like a pretty serious issue, which is why I think there is
some error in my understanding of the Enumeration process. Can anyone
correct me?
Thanks!
-Dave
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