# Counting the number of children when returning a parent

**URL:** <https://discuss.elastic.co/t/counting-the-number-of-children-when-returning-a-parent/9861>\
**Category:** Elasticsearch\
**Created:** [November 28, 2012, 12:48pm UTC](https://discuss.elastic.co/t/counting-the-number-of-children-when-returning-a-parent/9861 "2012-11-28T12:48:20Z")\
**Posts on this page:** 1\
**Showing post:** 5

<div class="post-metadata">

**Author:** ![Andrii\_Gakhov](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/andrii_gakhov/32/771_2.png) [@Andrii\_Gakhov](https://discuss.elastic.co/u/Andrii_Gakhov)\
**Post date:** [April 13, 2015, 3:45pm UTC](https://discuss.elastic.co/t/counting-the-number-of-children-when-returning-a-parent/9861/5 "2015-04-13T15:45:29Z")

</div>

Extending Martijn's approch to the current Elasticsearch 1.5, we can  
execute _inner\_hits_ together with _has\_child_ query, and get counts as the  
score for parent documents:

{  
"query": {  
"has\_child": {  
"type": "comment",  
"score\_mode": "sum",  
"query": {  
"match\_all": {}  
},  
"inner\_hits": {}  
}  
}  
}

Monday, 3 december 2012 г., 14:22:32 UTC+1 user Martijn v Groningen wrote:

> Another trick that might be interesting to test is to use the  
> `top_children` query and then set `score` to `sum` and wrap the child  
> query in a `constant_score` query. The score of the parent would then  
> tell you how many child documents have matched. This trick obviously  
> only is useable if you don't sort by relevance, but by something else  
> like a field or you don't care about the ordering of the hits. The  
> benefit of this approach is that only one search request needs to be  
> executed to get the parent documents with the child count.
> 
> Martijn
> 
> On 3 December 2012 22:47, davidconde \<da...@donedeal.ie \<javascript:\>\>  
> wrote:
> 
> > Thanks that seems to have done the job 🙂
> > 
> > On Wednesday, 28 November 2012 18:06:38 UTC, Radu Gheorghe wrote:
> > 
> > > Hello Dave,
> > > 
> > > It might help if you use a has\_parent query[0] and do a terms facet[1]  
> > > on  
> > > the \_parent field.
> > > 
> > > I've gisted an example here:  
> > > [Query parents and count children · GitHub](https://gist.github.com/4162883)
> > > 
> > > If that works for you, you might get better performance if you replace  
> > > the  
> > > query with a facet filter[2].
> > > 
> > > The downside of this approach is that the query itself will return the  
> > > children, not the parents. That said, you can take the parent IDs from  
> > > the  
> > > facet results and get the contents using the multi get API[3].
> > > 
> > > [0]
> 
> [Elasticsearch Platform — Find real-time answers at scale | Elastic](http://www.elasticsearch.org/guide/reference/query-dsl/has-parent-filter.html)
> 
> > > [1]
> 
> [Elasticsearch Platform — Find real-time answers at scale | Elastic](http://www.elasticsearch.org/guide/reference/api/search/facets/terms-facet.html)
> 
> > > [2]
> 
> [Elasticsearch Platform — Find real-time answers at scale | Elastic](http://www.elasticsearch.org/guide/reference/api/search/facets/index.html)
> 
> > > [3] [Elasticsearch Platform — Find real-time answers at scale | Elastic](http://www.elasticsearch.org/guide/reference/api/multi-get.html)
> > > 
> > > ## Best regards, Radu
> > > 
> > > [http://sematext.com/](http://sematext.com/) -- Elasticsearch -- Solr -- Lucene
> > > 
> > > On Wed, Nov 28, 2012 at 2:48 PM, davidconde [da...@donedeal.ie](mailto:da...@donedeal.ie) wrote:
> > > 
> > > > I have setup a parent child relationship and I would like to be able  
> > > > to  
> > > > return a list of parents but also include the count of children per  
> > > > parent.  
> > > > Is there an easy way to do this at the moment?
> > > > 
> > > > Thanks,  
> > > > Dave
> > > > 
> > > > --
> > 
> > --
> 
> --  
> Met vriendelijke groet,
> 
> Martijn van Groningen

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