[Xapian-discuss] xapian uses inverted index?

[James Aylett]

On Thu, Jul 13, 2006 at 03:17:34PM -0800, oscaruser at programmer.net wrote:

> Been looking the IR docs [http://www.xapian.org/docs/intro_ir.html],
> but didn't see anything about an inverted index. Is such a
> datastructure used by Xapian to help relevancy, improve search
> results or a method to determine context? e.g., "At a simple level a
> computerised IR system puts the terms in a direct access, or index
> file. A term can be looked up and its posting list found."

Inverted indexes can't really help relevancy and similar (at least, I
don't see how they can). They're basically a way of quickly figuring
out which documents contain which terms efficiently. They're essential
to practical implementations of the kind of IR system Xapian provides.

Xapian, in some ways, is just some smart algorithms on top of an
inverted index.

J

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  James Aylett                                                  xapian.org
  james at tartarus.org                               uncertaintydivision.org