# Synonym IDF documentation

**URL:** <https://discuss.elastic.co/t/synonym-idf-documentation/127948>\
**Category:** Elasticsearch\
**Created:** [April 13, 2018, 9:47am UTC](https://discuss.elastic.co/t/synonym-idf-documentation/127948 "2018-04-13T09:47:57Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![imranazad](https://avatars.discourse-cdn.com/v4/letter/i/c2a13f/32.png) [@imranazad](https://discuss.elastic.co/u/imranazad)\
**Post date:** [April 13, 2018, 9:47am UTC](https://discuss.elastic.co/t/synonym-idf-documentation/127948/1 "2018-04-13T09:47:57Z")

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Does the advice on the advantages and disadvantages of synonym expansion need updating:

[https://www.elastic.co/guide/en/elasticsearch/guide/current/synonyms-expand-or-contract.html](https://www.elastic.co/guide/en/elasticsearch/guide/current/synonyms-expand-or-contract.html)

It seems that query side or index side synonym expansion makes no difference to the IDF, on the queryside it seems that there is a Lucene SynonymQuery that merges the doc frequency count.

Can someone clarify this?

Thanks

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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:** [May 11, 2018, 9:47am UTC](https://discuss.elastic.co/t/synonym-idf-documentation/127948/2 "2018-05-11T09:47:59Z")

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Closed on May 11, 2018, 9:47am UTC

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