ElasticSearch - order with min in aggregation - elasticsearch

Question

I have objects in the index that are related by an id, which groups them.
The group creation time is the time between the min createdAt object in the group and the max createdAt object in the group.
I'd like to order these groups by the min or max time, how can I do this?
{
"size":0,
"aggs":{
"intervals":{
"composite":{
"size":10000,
"sources":[
{
"totalId":{
"terms":{
"field":"totalId"
}
},
"name": {
"terms":{
"field":"name"
}
}
}
]
},
"aggs": {
"createdAtStart": {
"min": {"field": "createdAt", "format": "YYYY-MM-DD'T'HH:mm:ssZ"}, "order": { "createdAtStart": "desc" }
},
"createdAtEnd": {
"max": {"field": "createdAt", "format": "YYYY-MM-DD'T'HH:mm:ssZ"}
}
}
}
}
I'm using order wrong:
Found two aggregation type definitions

Answer 1

You cannot achieve that with a composite aggregation because the terms source is not orderable by the values of a sub-aggregation, like it is the case with a "normal" terms aggregation. (also the date formats are wrong)
So the correct query that will give you want you want is this one:
{
"size": 0,
"aggs": {
"totalId": {
"terms": {
"field": "totalId",
"order": {
"createdAtStart": "asc"
}
},
"aggs": {
"createdAtStart": {
"min": {
"field": "createdAt",
"format": "yyyy-MM-dd'T'HH:mm:ssZ"
}
},
"createdAtEnd": {
"max": {
"field": "createdAt",
"format": "yyyy-MM-dd'T'HH:mm:ssZ"
}
}
}
}
}
}
Because of the way the composite aggregation works, it's not possible to achieve what you want. The reason is that the composite aggregation has been created in order to "paginate" over a big amount of buckets. That pagination is defined by the way the buckets are ordered. If it was possible to sort buckets according to sub-aggregations, it would mean that all buckets would need to be pre-computed and pre-sorted before returning the first page of results, which would completely defeat the purpose of this aggregation.

Answer 2

You are adding an extra {
{
"size": 0,
"aggs": {
"intervals": {
"composite": {
"size": 10000,
"sources": [
{
"totalId": {
"terms": {
"field": "totalId"
}
}
}
] <-- note this
},
"aggs": {
"createdAtStart": {
"min": {
"field": "createdAt",
"format": "YYYY-MM-DD'T'HH:mm:ssZ"
},
"order": {
"createdAtStart": "desc"
}
},
"createdAtEnd": {
"max": {
"field": "createdAt",
"format": "YYYY-MM-DD'T'HH:mm:ssZ"
}
}
}
}
}
}