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Subject: RE: Dates and others
Date: Mon, 1 Dec 2003 13:18:49 -0500
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Thread-Topic: Dates and others
Thread-Index: AcO4NngIkvw0HjYZRimnL8kW7MUG2gAAD5Mg
From: "Chong, Herb" <HChong3@bloomberg.com>
To: "Lucene Users List" <lucene-user@jakarta.apache.org>

ad hoc techniques run into lots of trouble because the requirement on =
Lucene isn't well specified. is a document with one of the search terms =
that is a week newer enough to move it ahead of a document that has all =
of the search terms? the boost mechanism is a way to move documents =
around in the ranking list, but it clearly is a way to reweight the =
importance of the query terms and not to impose external constraints =
that properly should be handled outside the search engine.

Herb...

-----Original Message-----
From: Doug Cutting [mailto:cutting@lucene.com]
Sent: Monday, December 01, 2003 1:11 PM
To: Lucene Users List
Subject: Re: Dates and others

The problem with this approach is that eventually you'll exhaust the=20
range of the boost.  So this will only work if you re-index things from=20
scratch periodically, with a boost of something like 1/days-ago.

If you're adding documents to the index in date order, then you could=20
use a HitCollector which adjusts scores according to the document=20
number, since document numbers increase as you add to the index.

If you're not adding things in date order, then you can, when you open=20
the index, build an array mapping document numbers to integer dates.=20
Then your hit collector can use this to either boost or sort hits by =
date.

Or you could add a "month" or "week" field to documents, then add it as=20
a clause to your queries with a boost.  Then documents matching the most =

recent week(s) and/or month(s) would get the boost.

Doug

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