# Why using parent/child relationship instead of a simple parent\_id relation?
**URL:** https://discuss.elastic.co/t/why-using-parent-child-relationship-instead-of-a-simple-parent-id-relation/12260
**Category:** Elasticsearch
**Created:** [June 4, 2013, 4:50pm UTC](https://discuss.elastic.co/t/why-using-parent-child-relationship-instead-of-a-simple-parent-id-relation/12260 "2013-06-04T16:50:56Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@Mathieu\_Roy](https://discuss.elastic.co/u/Mathieu_Roy)
#### Post date: [June 4, 2013, 4:50pm UTC](https://discuss.elastic.co/t/why-using-parent-child-relationship-instead-of-a-simple-parent-id-relation/12260/1 "2013-06-04T16:50:56Z")
I am asking myself why i would use a parent/child relationship to retrieve
childs docs instead of creating a parent\_id field in childs documents and
query on this field?
thank you
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### Author:  [@mattweber](https://discuss.elastic.co/u/mattweber)
#### Post date: [June 4, 2013, 4:57pm UTC](https://discuss.elastic.co/t/why-using-parent-child-relationship-instead-of-a-simple-parent-id-relation/12260/2 "2013-06-04T16:57:58Z")
Because you can execute queries against the parents and have the children
of the matching documents returned or vice versa. It is much more powerful
than simple filtering of a field.
On Tue, Jun 4, 2013 at 9:50 AM, Mathieu Roy [mr.math.roy@gmail.com](mailto:mr.math.roy@gmail.com) wrote:
> I am asking myself why i would use a parent/child relationship to retrieve
> childs docs instead of creating a parent\_id field in childs documents and
> query on this field?
>
> thank you
>
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### Author:  [@Mathieu\_Roy](https://discuss.elastic.co/u/Mathieu_Roy)
#### Post date: [June 4, 2013, 5:41pm UTC](https://discuss.elastic.co/t/why-using-parent-child-relationship-instead-of-a-simple-parent-id-relation/12260/3 "2013-06-04T17:41:01Z")
ah ok, i understand better now.
Thank you
Le mardi 4 juin 2013 12:57:58 UTC-4, Matt Weber a écrit :
> Because you can execute queries against the parents and have the children
> of the matching documents returned or vice versa. It is much more powerful
> than simple filtering of a field.
>
> On Tue, Jun 4, 2013 at 9:50 AM, Mathieu Roy \<[mr.ma...@gmail.com](mailto:mr.ma...@gmail.com)\
>
> > wrote:
>
> > I am asking myself why i would use a parent/child relationship to
> > retrieve childs docs instead of creating a parent\_id field in childs
> > documents and query on this field?
> >
> > thank you
> >
> > --
> > You received this message because you are subscribed to the Google Groups
> > "elasticsearch" group.
> > To unsubscribe from this group and stop receiving emails from it, send an
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### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [July 6, 2017, 2:33am UTC](https://discuss.elastic.co/t/why-using-parent-child-relationship-instead-of-a-simple-parent-id-relation/12260/4 "2017-07-06T02:33:02Z")