Elasticsearchのドキュメント内にあった、Nested Objectsを実際に、senseで実行します。
indexの作成
PUT /my_index
{
"mappings": {
"blogpost": {
"properties": {
"comments": {
"type": "nested",
"properties": {
"name": { "type": "string" },
"comment": { "type": "string" },
"age": { "type": "short" },
"stars": { "type": "short" },
"date": { "type": "date" }
}
}
}
}
}
}
データ挿入
PUT /my_index/blogpost/1
{
"title": "Nest eggs",
"body": "Making your money work...",
"tags": [ "cash", "shares" ],
"comments": [
{
"name": "John Smith",
"comment": "Great article",
"age": 28,
"stars": 4,
"date": "2014-09-01"
},
{
"name": "Alice White",
"comment": "More like this please",
"age": 31,
"stars": 5,
"date": "2014-10-22"
}
]
}
PUT /my_index/blogpost/2
{
"title": "Investment secrets",
"body": "What they don't tell you ...",
"tags": [ "shares", "equities" ],
"comments": [
{
"name": "Mary Brown",
"comment": "Lies, lies, lies",
"age": 42,
"stars": 1,
"date": "2014-10-18"
},
{
"name": "John Smith",
"comment": "You're making it up!",
"age": 28,
"stars": 2,
"date": "2014-10-16"
}
]
}
検索
ブログのタイトルがeggsが含まれており、johnという名前の含まれた28歳がコメントしたものを検索します。Array Objectと違って、どちらも満たしていないと検索結果に現れません。
# クエリ
GET /my_index/blogpost/_search
{
"query": {
"bool": {
"must": [
{
"match": {
"title": "eggs"
}
},
{
"nested": {
"path": "comments",
"query": {
"bool": {
"must": [
{
"match": {
"comments.name": "john"
}
},
{
"match": {
"comments.age": 28
}
}
]
}
}
}
}
]
}}}
# 結果
{
"took": 1,
"timed_out": false,
"_shards": {
"total": 5,
"successful": 5,
"failed": 0
},
"hits": {
"total": 1,
"max_score": 1.8257527,
"hits": [
{
"_index": "my_index",
"_type": "blogpost",
"_id": "1",
"_score": 1.8257527,
"_source": {
"title": "Nest eggs",
"body": "Making your money work...",
"tags": [
"cash",
"shares"
],
"comments": [
{
"name": "John Smith",
"comment": "Great article",
"age": 28,
"stars": 4,
"date": "2014-09-01"
},
{
"name": "Alice White",
"comment": "More like this please",
"age": 31,
"stars": 5,
"date": "2014-10-22"
}
]
}
}
]
}
}
ソートも試しています。
GET /my_index/blogpost/_search
{
"query": {
"nested": {
"path": "comments",
"filter": {
"range": {
"comments.date": {
"gte": "2014-10-01",
"lt": "2014-11-01"
}
}
}
}
},
"sort": {
"comments.stars": {
"order": "asc",
"mode": "min",
"nested_filter": {
"range": {
"comments.date": {
"gte": "2014-10-01",
"lt": "2014-11-01"
}
}
}
}
}
}
Aggregation
コメントの平均スター数を月別に取得します。
# クエリ
GET /my_index/blogpost/_search
{
"size" : 0,
"aggs": {
"comments": {
"nested": {
"path": "comments"
},
"aggs": {
"by_month": {
"date_histogram": {
"field": "comments.date",
"interval": "month",
"format": "yyyy-MM"
},
"aggs": {
"avg_stars": {
"avg": {
"field": "comments.stars"
}
}
}
}
}
}
}
}
# 結果
{
"took": 20,
"timed_out": false,
"_shards": {
"total": 5,
"successful": 5,
"failed": 0
},
"hits": {
"total": 2,
"max_score": 0,
"hits": []
},
"aggregations": {
"comments": {
"doc_count": 4,
"by_month": {
"buckets": [
{
"key_as_string": "2014-09",
"key": 1409529600000,
"doc_count": 1,
"avg_stars": {
"value": 4
}
},
{
"key_as_string": "2014-10",
"key": 1412121600000,
"doc_count": 3,
"avg_stars": {
"value": 2.6666666666666665
}
}
]
}
}
}
}
reverse_nested Aggregation
ネスト検索された結果に対して、ネストされているフィールドの外側（今回だと、tags)の集計を取得できる。
# クエリ
GET /my_index/blogpost/_search
{
"size" : 0,
"aggs": {
"comments": {
"nested": {
"path": "comments"
},
"aggs": {
"age_group": {
"histogram": {
"field": "comments.age",
"interval": 10
},
"aggs": {
"blogposts": {
"reverse_nested": {},
"aggs": {
"tags": {
"terms": {
"field": "tags"
}
}
}
}
}
}
}
}
}
}
# 結果
{
"took": 8,
"timed_out": false,
"_shards": {
"total": 5,
"successful": 5,
"failed": 0
},
"hits": {
"total": 2,
"max_score": 0,
"hits": []
},
"aggregations": {
"comments": {
"doc_count": 4,
"age_group": {
"buckets": [
{
"key": 20,
"doc_count": 2,
"blogposts": {
"doc_count": 2,
"tags": {
"doc_count_error_upper_bound": 0,
"sum_other_doc_count": 0,
"buckets": [
{
"key": "shares",
"doc_count": 2
},
{
"key": "cash",
"doc_count": 1
},
{
"key": "equities",
"doc_count": 1
}
]
}
}
},
{
"key": 30,
"doc_count": 1,
"blogposts": {
"doc_count": 1,
"tags": {
"doc_count_error_upper_bound": 0,
"sum_other_doc_count": 0,
"buckets": [
{
"key": "cash",
"doc_count": 1
},
{
"key": "shares",
"doc_count": 1
}
]
}
}
},
{
"key": 40,
"doc_count": 1,
"blogposts": {
"doc_count": 1,
"tags": {
"doc_count_error_upper_bound": 0,
"sum_other_doc_count": 0,
"buckets": [
{
"key": "equities",
"doc_count": 1
},
{
"key": "shares",
"doc_count": 1
}
]
}
}
}
]
}
}
}
}