# Unique field query in Timelion

**URL:** <https://discuss.elastic.co/t/unique-field-query-in-timelion/95847>\
**Category:** Kibana\
**Tags:** timelion\
**Created:** [August 4, 2017, 9:28am UTC](https://discuss.elastic.co/t/unique-field-query-in-timelion/95847 "2017-08-04T09:28:26Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![sLuvpreet33](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/sluvpreet33/32/50626_2.png) [@sLuvpreet33](https://discuss.elastic.co/u/sLuvpreet33)\
**Post date:** [August 4, 2017, 9:28am UTC](https://discuss.elastic.co/t/unique-field-query-in-timelion/95847/1 "2017-08-04T09:28:27Z")

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I want to make a visualization using Timelion.

I want to plot the count of documents only where a field is unique. In my case it is the user\_id of the user.

How do I put the condition that some field should be unique in Timelion expression ?

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<div class="post-metadata">

**Author:** ![Marius\_Dragomir](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/marius_dragomir/32/42087_2.png) [@Marius\_Dragomir](https://discuss.elastic.co/u/Marius_Dragomir)\
**Post date:** [August 8, 2017, 1:33pm UTC](https://discuss.elastic.co/t/unique-field-query-in-timelion/95847/2 "2017-08-08T13:33:27Z")

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Hello,  
You can use the Cardinality metric for this.  
`.es(*, metric='cardinality:user_id')`

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<div class="post-metadata">

**Author:** ![sLuvpreet33](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/sluvpreet33/32/50626_2.png) [@sLuvpreet33](https://discuss.elastic.co/u/sLuvpreet33)\
**Post date:** [August 8, 2017, 6:09pm UTC](https://discuss.elastic.co/t/unique-field-query-in-timelion/95847/3 "2017-08-08T18:09:16Z")

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Thank you. It was helpful.  
Can you please elaborate this cardinality thing ?

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<div class="post-metadata">

**Author:** ![Marius\_Dragomir](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/marius_dragomir/32/42087_2.png) [@Marius\_Dragomir](https://discuss.elastic.co/u/Marius_Dragomir)\
**Post date:** [August 8, 2017, 6:30pm UTC](https://discuss.elastic.co/t/unique-field-query-in-timelion/95847/4 "2017-08-08T18:30:57Z")

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It's a term commonly used in SQL for counting the number of unique elements in a set.

> **[Cardinality (SQL statements)](https://en.wikipedia.org/wiki/Cardinality_(SQL_statements))**
>
> In SQL (Structured Query Language), the term cardinality refers to the uniqueness of data values contained in a particular column (attribute) of a database table. The lower the cardinality, the more duplicated elements in a column. Thus, a column with the lowest possible cardinality would have the same value for every row. SQL databases use cardinality to help determine the optimal query plan for a given query. When dealing with columnar value sets, there are three types of cardinality: high-car...

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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:** [September 5, 2017, 6:31pm UTC](https://discuss.elastic.co/t/unique-field-query-in-timelion/95847/5 "2017-09-05T18:31:06Z")

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