Newbie Question boosting

[ayyanar <ay...@aspiresys.com>]

I read many articles on boosting still iam not so clear on boosting. Can
anyone explain the following questions with examples?

1) Can you given an example for field level boosting and document level
boosting and the difference between two?

2) If we set the boost at field level (index time), should the query
contains the that particular field?
For example, if we set the boost for title field, should we create the
termquery for title field?

Also, based on your experience, can you explain why you need the boosting.

Thanks,
Ayyanar. A
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Re: Newbie Question boosting

[Erick Erickson <er...@gmail.com>]

I can help a bit with <2>...

First, keep in mind the difference between index and query
time boosting:

>From Hossman:
..Index time field bosts are a way to express things like
"this documents title is worth twice as much as the title of most documents"
query time boosts are a way to express "i care about matches on this clause
of my query twice as much as i do about matches to other clauses of my
query".

Boosting doesn't do anything if your search doesn't use the field you've
boosted
on, but that's only relevant for index-time boosts. You can't have a
query-time
boost that doesn't reference the field since that's how you boost at query
time by definition.

So, say you have documents that you think are more important than
run-of-the-mill
documents. An example could be an animals database. You might want
documents from scholarly sources to have a greater weight, thus be more
likely
to appear at the top of your search results. These would be fine documents
to
boost the fields for at index time. That would mean that the scholarly
documents
would tend to be higher up in your search results.

For query time, say you have a genealogy database. Books in this category
often have
titles like "The Erickson family history in New England, 1700-1930". Now say
you
have separate fields for title and text. A user searches for "erickson". You
want the
title to weigh much more than the text since it's much more likely that the
user
would find that document more valuable than some document about the Swanson
family that mentions somewhere in the text that Olaf Swanson married Edna
Erickson. So you'd form some query like: title:erickson^10 text:erickson


HTH
Erick

On Thu, Dec 11, 2008 at 1:47 AM, ayyanar
<ay...@aspiresys.com>wrote:

>
> I read many articles on boosting still iam not so clear on boosting. Can
> anyone explain the following questions with examples?
>
> 1) Can you given an example for field level boosting and document level
> boosting and the difference between two?
>
> 2) If we set the boost at field level (index time), should the query
> contains the that particular field?
> For example, if we set the boost for title field, should we create the
> termquery for title field?
>
> Also, based on your experience, can you explain why you need the boosting.
>
> Thanks,
> Ayyanar. A
> --
> View this message in context:
> http://www.nabble.com/Newbie-Question-boosting-tp20950268p20950268.html
> Sent from the Solr - User mailing list archive at Nabble.com.
>
>