# When ES excludes fields from source
**URL:** https://discuss.elastic.co/t/when-es-excludes-fields-from-source/11991
**Category:** Elasticsearch
**Created:** [May 16, 2013, 8:20am UTC](https://discuss.elastic.co/t/when-es-excludes-fields-from-source/11991 "2013-05-16T08:20:07Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@Pawel\_Mlynarczyk](https://discuss.elastic.co/u/Pawel_Mlynarczyk)
#### Post date: [May 16, 2013, 8:20am UTC](https://discuss.elastic.co/t/when-es-excludes-fields-from-source/11991/1 "2013-05-16T08:20:07Z")
Hello everyone
I'd like to know, when does excluding fields from source take place? (When
the document is being written or each time it is read?)
Also, does excluding have a big impact on performance?
Would that be better to group all excluded fields in one path and use a
wildcard ("path.\*") instead of having multiple excluded fields all around
the document?
Thanks in advance
Paweł Młynarczyk
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### Author:  [@Boaz\_Leskes](https://discuss.elastic.co/u/Boaz_Leskes)
#### Post date: [May 16, 2013, 3:11pm UTC](https://discuss.elastic.co/t/when-es-excludes-fields-from-source/11991/2 "2013-05-16T15:11:23Z")
Hi Pawel,
The exclude and include settings of the \_source mapping are applied just
before the document is stored in the index. It is a very light weight
operation. Performance wise it doesn't really matter if you wild cards or
not. I would just whatever feels more tidy to you.
Cheers,
Boaz
On Thursday, May 16, 2013 10:20:07 AM UTC+2, Paweł Młynarczyk wrote:
> Hello everyone
>
> I'd like to know, when does excluding fields from source take place? (When
> the document is being written or each time it is read?)
> Also, does excluding have a big impact on performance?
> Would that be better to group all excluded fields in one path and use a
> wildcard ("path.\*") instead of having multiple excluded fields all around
> the document?
>
> Thanks in advance
> Paweł Młynarczyk
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### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [July 6, 2017, 2:36am UTC](https://discuss.elastic.co/t/when-es-excludes-fields-from-source/11991/3 "2017-07-06T02:36:16Z")