How to sort an ElasticSearch index using a field inside an array?

Question

I need to sort documents in my elastic index using a field inside an array in that document. Document structure looks like this,

{
  'name':'xxxxx',
  'comments':[
     {comment: 'xxxxx', 'commentDate':'yyyy-MM-dd HH:mm:ss', 'id':1},
     {comment: 'xxxxx', 'commentDate':'yyyy-MM-dd HH:mm:ss', 'id':2}
   ]
}

What I want to do is sort the documents based on the commentDate field to get the documents with latest comments first. So far I've think of keeping separate field inside the document to track the last comment date. So the document becomes,

{
  'name':'xxxxx',
  'comments':[
     {comment: 'xxxxx', 'commentDate':'yyyy-MM-dd HH:mm:ss', 'id':1},
     {comment: 'xxxxx', 'commentDate':'yyyy-MM-dd HH:mm:ss', 'id':2}
   ],
  'lastCommentDate': 'yyyy-MM-dd HH:mm:ss'
}

I'd like to know whether is this the best way of doing this or is it possible to do this using script sort without changing the index?

I'm using Elastic API for Java and it would be very much appreciated if you can show me how to do this without changing the index. Also, I want to get the sorted data set directly from ES, so sorting after fetching data is not what I'm looking for

Elastic version : 5.1.1

Also, are you setting the mapping of the index before ingesting the data? — Amriteya
– Amriteya, Commented Jan 25, 2018 at 7:11
That could be the problem. When you index automatically without setting the mapping, the nested documents don't get mapped properly. — Amriteya
– Amriteya, Commented Jan 25, 2018 at 20:35

Amriteya · Accepted Answer · 2020-01-24 16:43:15Z

1

If you're ingesting data without creating a mapping on the index, Elasticsearch will flatten the nested documents.

Elasticsearch does this to speed up the query although it is not suitable in cases like these.

Make sure you create a custom mapping before ingesting the data to be indexed.

answered Jan 24, 2020 at 16:43

Amriteya

1,1921 gold badge17 silver badges38 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

How to sort an ElasticSearch index using a field inside an array?

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related