# Dictionary\_decompounder needs lowercase word lists if "lowercase" filter is used for query -\> gotcha/bug?

**URL:** <https://discuss.elastic.co/t/dictionary-decompounder-needs-lowercase-word-lists-if-lowercase-filter-is-used-for-query-gotcha-bug/52435>\
**Category:** Elasticsearch\
**Created:** [June 10, 2016, 11:06am UTC](https://discuss.elastic.co/t/dictionary-decompounder-needs-lowercase-word-lists-if-lowercase-filter-is-used-for-query-gotcha-bug/52435 "2016-06-10T11:06:33Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Felix\_Schwarz](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/felix_schwarz/32/1530_2.png) [@Felix\_Schwarz](https://discuss.elastic.co/u/Felix_Schwarz)\
**Post date:** [June 10, 2016, 11:06am UTC](https://discuss.elastic.co/t/dictionary-decompounder-needs-lowercase-word-lists-if-lowercase-filter-is-used-for-query-gotcha-bug/52435/1 "2016-06-10T11:06:33Z")

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I noticed some behavior which was very confusing to me and it took me a bit of time to find out the root cause. Now I'm looking for advise if this is a widely accepted "gotcha" or might be even considered a bug.

Basically I want to use ElasticSearch's "dictionary\_decompounder" and "hyphenation\_decompounder" filters (ElasticSearch 2.3.3). Both get a word list as input. Well, there are a lot of word files available so getting the data is no problem.

Now I also treat searches case-insensitively ("lowercase" filter). However I noticed that decompounding does not work UNLESS all items in the the word list/file are also lower-cased.

Somehow I can understand that requirement (it is similar to using the same tokenization for indexing and searching) but anyway it took my quite some time to realize. I think this should be mentioned in the docs at least (gotcha) but I'm not sure what phrasing would be best.

Ideally I would like ElasticSearch to process my word lists so I can just drop in unmodified files from external sources without preprocessing but that seems to be a minor issue.

Any suggestions how I should proceed? As I never contributed to ElasticSearch so far some advise about the bug reporting process/documentation enhancements are appreciated.  
Felix

(I suspect the problem did not occur to many users so far as it seems only German uses compound words AND capitalized nouns - unfortunately the majority of compound words in German are made of nouns. So capitalization is a pretty big deal here.)

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**Author:** ![Jan\_Apel](https://avatars.discourse-cdn.com/v4/letter/j/6bbea6/32.png) [@Jan\_Apel](https://discuss.elastic.co/u/Jan_Apel)\
**Post date:** [July 11, 2016, 9:37am UTC](https://discuss.elastic.co/t/dictionary-decompounder-needs-lowercase-word-lists-if-lowercase-filter-is-used-for-query-gotcha-bug/52435/2 "2016-07-11T09:37:15Z")

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I noticed the same behavior... It would be awesome if there was a setting like for the Hunspell Token Filter ([https://www.elastic.co/guide/en/elasticsearch/reference/current/analysis-hunspell-tokenfilter.html](https://www.elastic.co/guide/en/elasticsearch/reference/current/analysis-hunspell-tokenfilter.html)) to just ignore\_case

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**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [July 5, 2017, 10:36pm UTC](https://discuss.elastic.co/t/dictionary-decompounder-needs-lowercase-word-lists-if-lowercase-filter-is-used-for-query-gotcha-bug/52435/3 "2017-07-05T22:36:39Z")

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