# Question regarding Customizing fields.yml

**URL:** <https://discuss.elastic.co/t/question-regarding-customizing-fields-yml/215176>\
**Category:** Beats\
**Tags:** filebeat\
**Created:** [January 15, 2020, 4:57pm UTC](https://discuss.elastic.co/t/question-regarding-customizing-fields-yml/215176 "2020-01-15T16:57:02Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![john\_eapen](https://avatars.discourse-cdn.com/v4/letter/j/b3f665/32.png) [@john\_eapen](https://discuss.elastic.co/u/john_eapen)\
**Post date:** [January 15, 2020, 4:57pm UTC](https://discuss.elastic.co/t/question-regarding-customizing-fields-yml/215176/1 "2020-01-15T16:57:02Z")

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Hi there,

Just wanted to know what the general guidelines/best practices are regarding fields.yml which is used for creating index template.

The out-of-box fields.yml has hundreds of fields and we are not even using most of it.

1- Is it a good practice to remove the unwanted fields and actually add our own custom fields into fields.yml ?.

2- Can the out-of-box fields.yml cause performance issue since there are so many fields. Does ES internally really care about the unused fields. (fields with no data).?

3- If we do customize, then are "setup.template.name|pattern|fields" the correct config properties to set.

Thanks  
John

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**Author:** ![shaunak](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/shaunak/32/6643_2.png) [@shaunak](https://discuss.elastic.co/u/shaunak)\
**Post date:** [January 15, 2020, 10:03pm UTC](https://discuss.elastic.co/t/question-regarding-customizing-fields-yml/215176/2 "2020-01-15T22:03:17Z")

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I wouldn't recommend messing with the out-of-the-box `fields.yml`. Instead I'd recommend creating your own and then using `setup.template.name|pattern|fields`.

Shaunak

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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:** [February 12, 2020, 10:03pm UTC](https://discuss.elastic.co/t/question-regarding-customizing-fields-yml/215176/3 "2020-02-12T22:03:26Z")

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