# Tags with variable boost values

**URL:** <https://discuss.elastic.co/t/tags-with-variable-boost-values/14313>\
**Category:** Elasticsearch\
**Created:** [November 8, 2013, 12:42am UTC](https://discuss.elastic.co/t/tags-with-variable-boost-values/14313 "2013-11-08T00:42:40Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![zellster](https://avatars.discourse-cdn.com/v4/letter/z/ea666f/32.png) [@zellster](https://discuss.elastic.co/u/zellster)\
**Post date:** [November 8, 2013, 12:42am UTC](https://discuss.elastic.co/t/tags-with-variable-boost-values/14313/1 "2013-11-08T00:42:40Z")

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I am trying to model a document that has a collection of tags where the tag  
boost value depends on the total number of the tags in said document. The  
operating assumption is that the more tags a document has, the less boost  
each matching tag should have on a query. In this example, let's assume  
that a document can have at most 5 tags. For a concrete example, document  
1 has two tags: "foo" and "bar". Calculating the boost value for each tag  
works as follows in pseudo-Ruby:

1. Calculate the total number of points for the overall boost in the  
document:

total, val = 0, 5

tags.each { |tag|  
total += val; val -= 1  
}

For document 1, total = (5 + 4)

1. Calculate each tag boost given the tag's position and the total number  
of points

val = 5

tags.each { |tag|  
tag.boost = val / total; val -= 1  
}

"foo" has a boost of (5 / 9), while "bar" has (4 / 9).

Any other document where the number of tags is != 2 will have different  
boost values per tag. Because of this, I don't think query-time boosting  
is a good fit.

One option I have thought of is to create 5 new strings in the schema:  
tag\_1 to tag\_5. Each string will contain a tag, and its associated boost  
value set at index time. Then a query would match against tag\_1 to tag\_5  
instead of the tags collection. Is there a cleaner way to do this?

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---

<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [July 6, 2017, 2:08am UTC](https://discuss.elastic.co/t/tags-with-variable-boost-values/14313/2 "2017-07-06T02:08:16Z")

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