You might have a look at using a phrase query when you have more than
one term in the query in addition to your term query, but giving the
phrase query more weight (i.e. give an exact match more weight) and
keep your original tokenization process.
Something like:
"NW10 7NY"^5 OR NW10 OR 7NY
or even downweighting the individual terms. Thus, exact matches on
the full phrase will weigh much higher, and you can still do
individual term matching for the single term case (NW10)
-Grant
On May 6, 2008, at 12:28 PM, Chris Mannion wrote:
Hi all
I've got a bit of a niggling problem with how one of my searches is
working
as opposed to how my users would like it too work. We're indexing
on UK
postcodes, which are in the format of a 3 or 4 character area code
followed
by a 3 or 4 character street specific code, e.g. "NW10 7NY" or "M11
1LQ".
We originally had the values being indexed as tokenized and used a
very
simple search string in the format "postcode:xxx xxx", with no
grouping or
boosting or fuzzy searching, just an straight search on whatever the
user
answered. This had the benefit of finding exact matches to searches
and
allowing us to search just on the area part of the code to return all
records with that area code, eg a search on "NW2" returning anything
starting NW2, like "NW2 6TB", "NW2 1ER" etc etc.
However, the downside to that was that searches could also return
records
only tenuously related to what was searched for, eg. a search for
"NW10 7NY"
would also return a record with a postcode "SE9 6NY" because of the
slight
match of the "NY". Obviously this was technically correct but users
complained because their searches were returning records from
completely
different areas. Our first step to put this right was to take off the
tokenization of the field, which we also weren't happy with so have
continued to fiddle.
The current status is as follows - we index the values by stripping
out
spaces and tokeniing them and use a keywordAnalyzer. In searching
we also
strip spaces from the search term entered and search with a
keywordAnalyzer. Searches for full postcodes, e.g. "NW10 7NY" find
all
exact matches but also any full values that are partial matches
(e.g. some
records just have "NW10" as their postcode field and the "NW10 7NY"
search
pulls them back too), but searches for partial postcodes e.g. "NW10"
still
only finds exact matches, e.g. it only pulls back those record that
have
just "NW10" as their postcode, rather than anything *starting* with
NW10 as
we'd like it to do.
Can anyone help me get this working in the way we need it too please?
--
Chris Mannion
iCasework and LocalAlert implementation team
0208 144 4416
--------------------------
Grant Ingersoll
Lucene Helpful Hints:
http://wiki.apache.org/lucene-java/BasicsOfPerformance
http://wiki.apache.org/lucene-java/LuceneFAQ
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