I'm developing an application used by scientists -- people who have a pretty
good idea of what logic is -- and they were shocked to find out that neither
of these queries return the same results:
1- banana AND apple OR orange
2- banana AND (apple OR orange)
3- (banana AND apple) OR orange
I'd expect (1) to be either (2) or (3), but it turns out it's parsed as
"+banana apple orange". I was rather, uh, dismayed by this find, as it
doesn't seem to make sense.
I just spent half a day reading up on the various ways QueryParser is
broken, by going through the bugs and the mailing-list archives. And I'm
still unable to come to a conclusion. Here's where I'm at:
a- queries which mix boolean operators require strict parenthesizing to
work right
b- "+" isn't shorthand for "AND"; using it with "AND"/"OR"/"NOT" and the
default operator "" rarely does what you expect
c- the stock QueryParser doesn't work well in these cases
d- there's a new PrecedenceQueryParser at
http://svn.apache.org/repos/asf/lucene/java/trunk/contrib/miscellaneous that
solves *some* of the issues but creates others
e- there is a non-Lucene effort to create a query parser with a
different syntax at http://famestalker.com/devwiki/
While we are also developing a query-building UI, users must be able to
enter text queries as well. What do other folks do? I mean, this is pretty
bad. I can hardly go back to my scientists and tell them Lucene is unable to
handle 2 boolean operators, that they should parenthesize everything by
hand. I mean, that's just cheesy.
--Renaud
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