Elasticsearch get n ordered records and then apply grouping - elasticsearch

Question

Here's an example of what I'm looking for. Let's say I have records of some purchases. I want to get records where price is > $50 and order by price descending. I want to limit those ordered records to 100 and then group them by zip code.
Final result should have counts of hits for each zip where sum of those counts would total to 100 record.
ES v2.1.1

Answer 1

what do you mean by "group them by zip code":
just want to know the number of docs in the group?
a hash with zip code as the key associated with docs?
If 1:
{
"size": 100,
"query": {
"filtered": {
"filter": {
"range": {
"price": {
"gt": 50
}
}
}
}
},
"sort": {
"price": "desc"
},
"aggs": {
"by_zip_code": {
"terms": {
"field": "zip_code"
}
}
}
}
If 2, you may use the top hits aggregations. However, sorting by price is not possible (how could we do that?), and by default Elasticsearch uses the _count (check intrinsic sorts out). If the sort is not a big deal, the following will work:
{
"size": 0,
"query": {
"filtered": {
"filter": {
"range": {
"price": {
"gt": 50
}
}
}
}
},
"sort": {
"price": "desc"
},
"aggs": {
"by_zip_code": {
"terms": {
"field": "zip_code",
"size": 100
},
"aggs": {
"hits": {
"top_hits": {}
}
}
}
}
}

Answer 2

You need to use the Search API to get the 100 results and then post-process to perform the aggregation (since an aggregation of top hits cannot be done directly using the ES API).
"I want to get records where price is > $50" - You need a range filter.
"...order by price descending" - You need a sort.
"I want to limit those ordered records to 100" - You need to specify
the size parameter.
"...then group them by zip code" - You need to post-process the "hits":"hits" array to do this (e.g. inserting into a hash table / dictionary with zip code as the key values).
For steps 1-3 you need:
$ curl -XGET 'http://localhost:9200/my_index/_search?pretty' -d '{"query":
{"filtered" : {"filter" : { "range": { "price": { "gt": 50 }}}}},
"size" : 100,
"sort": { "price": { "order": "desc" }}
}'