Pravin Shinde wrote:
I am trying to use Leading wildcard query, but I am not able to do it.
Any query with leading wildcard is failing with lexical error.
query = parser.parse( "*hi" )
JavaError: org.apache.lucene.queryParser.ParseException:
Lexical error at line 1, column 1. Encountered: "*" (42), after : ""
I came across some documentation in Lucene FAQ which says
http://wiki.apache.org/jakarta-lucene/LuceneFAQ#head-4d62118417eaef0dcb87f4370583f809848ea695
Note: Leading wildcards (e.g. *ook) are not supported by the
QueryParser (although Lucene could handle them -- see the comment in
QueryParser.jj to enable these kind of queries -- search for "OG: to
support prefix queries:").
Is there any way I can do Leading wildchard query ?
You could implement something, but it would have to be done differently
to how wildcard queries are currently done. A wildcard query expands to
match all possible tokens that match that pattern currently in the index
(restricted to that field). I think the way the index is set up makes it
possible to build this list when you know at least the first character.
By starting with a * you need to get the complete list of tokens, then
filter out those that don't match. I imagine this would be quite slow,
hence why it's not in Lucene at the moment.
Miles
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