Elasticsearch不仅仅适合做全文检索，分析聚合功能也很好用。下面通过实例来学习。
一、准备数据
{"index":{ "_index": "books", "_type": "IT", "_id": "1" }}
{"id":"1","title":"Java编程思想","language":"java","author":"Bruce Eckel","price":70.20,"year": 2007,"description":"Java学习必读经典,殿堂级著作！赢得了全球程序员的广泛赞誉。"}
{"index":{ "_index": "books", "_type": "IT", "_id": "2" }}
{"id":"2","title":"Java程序性能优化","language":"java","author":"葛一鸣","price":46.50,"year": 2012,"description":"让你的Java程序更快、更稳定。深入剖析软件设计层面、代码层面、JVM虚拟机层面的优化方法"}
{"index":{ "_index": "books", "_type": "IT", "_id": "3" }}
{"id":"3","title":"Python科学计算","language":"python","author":"张若愚","price":81.40,"year": 2016,"description":"零基础学python,光盘中作者独家整合开发winPython运行环境，涵盖了Python各个扩展库"}
{"index":{ "_index": "books", "_type": "IT", "_id": "4" }}
{"id":"4","title":"Python基础教程","language":"python","author":"张若愚","price":54.50,"year": 2014,"description":"经典的Python入门教程，层次鲜明，结构严谨，内容翔实"}
{"index":{ "_index": "books", "_type": "IT", "_id": "5" }}
{"id":"5","title":"JavaScript高级程序设计","language":"javascript","author":"Nicholas C.Zakas","price":66.40,"year":2012,"description":"JavaScript技术经典名著"}准备5条数据，保存着books.json中，批量导入：
curl -XPOST "http://localhost:9200/_bulk?pretty" --data-binary @books.json二、Group By分组统计
执行命令:
curl -XPOST "http://localhost:9200/books/_search?pretty" -d '{
"size": 0,
"aggs": {
"per_count": {
"terms": {
"field": "language"
}
}
}
}'统计结果：
{
"took" : 3,
"timed_out" : false,
"_shards" : {
"total" : 5,
"successful" : 5,
"failed" : 0
},
"hits" : {
"total" : 5,
"max_score" : 0.0,
"hits" : [ ]
},
"aggregations" : {
"per_count" : {
"doc_count_error_upper_bound" : 0,
"sum_other_doc_count" : 0,
"buckets" : [ {
"key" : "java",
"doc_count" : 2
}, {
"key" : "python",
"doc_count" : 2
}, {
"key" : "javascript",
"doc_count" : 1
} ]
}
}
}按编程语言分类，java类2本，python类1本，javascript类1本。
三、Max最大值
执行命令，统计price最大的：
curl -XPOST "http://localhost:9200/books/_search?pretty" -d '{
"size": 0,
"aggs": {
"max_price": {
"max": {
"field": "price"
}
}
}
}'返回结果：
{
"took" : 2,
"timed_out" : false,
"_shards" : {
"total" : 5,
"successful" : 5,
"failed" : 0
},
"hits" : {
"total" : 5,
"max_score" : 0.0,
"hits" : [ ]
},
"aggregations" : {
"max_price" : {
"value" : 81.4
}
}
}四、Min最小值
求价格最便宜的那本：
curl -XPOST "http://localhost:9200/books/_search?pretty" -d '{
"size": 0,
"aggs": {
"max_price": {
"max": {
"field": "price"
}
}
}
}'统计结果：
{
"took" : 3,
"timed_out" : false,
"_shards" : {
"total" : 5,
"successful" : 5,
"failed" : 0
},
"hits" : {
"total" : 5,
"max_score" : 0.0,
"hits" : [ ]
},
"aggregations" : {
"max_price" : {
"value" : 81.4
}
}
}五、Average平均值
分组统计并求5本书的平均价格：
curl -XPOST "http://localhost:9200/books/_search?pretty" -d '{
"size": 0,
"aggs": {
"per_count": {
"terms": {
"field": "language"
},
"aggs": {
"avg_price": {
"avg": {
"field": "price"
}
}
}
}
}
}
'返回结果：
{
"took" : 4,
"timed_out" : false,
"_shards" : {
"total" : 5,
"successful" : 5,
"failed" : 0
},
"hits" : {
"total" : 5,
"max_score" : 0.0,
"hits" : [ ]
},
"aggregations" : {
"per_count" : {
"doc_count_error_upper_bound" : 0,
"sum_other_doc_count" : 0,
"buckets" : [ {
"key" : "java",
"doc_count" : 2,
"avg_price" : {
"value" : 58.35 }
}, {
"key" : "python",
"doc_count" : 2,
"avg_price" : {
"value" : 67.95 }
}, {
"key" : "javascript",
"doc_count" : 1,
"avg_price" : {
"value" : 66.4 }
} ]
}
}
}六、Sum求和
求5本书总价：
curl -XPOST "http://localhost:9200/books/_search?pretty" -d '
{
"size": 0,
"aggs": {
"sum_price": {
"sum": {
"field": "price"
}
}
}
}'返回结果：
{
"took" : 6,
"timed_out" : false,
"_shards" : {
"total" : 5,
"successful" : 5,
"failed" : 0
},
"hits" : {
"total" : 5,
"max_score" : 0.0,
"hits" : [ ]
},
"aggregations" : {
"sum_price" : {
"value" : 319.0
}
}
}七、基本统计
基本统计会返回字段的最大值、最小值、平均值、求和：
curl -XPOST "http://localhost:9200/books/_search?pretty" -d '{
"size": 0,
"aggs": {
"grades_stats": {
"stats": {
"field": "price"
}
}
}
}'返回结果：
{
"took" : 2,
"timed_out" : false,
"_shards" : {
"total" : 5,
"successful" : 5,
"failed" : 0
},
"hits" : {
"total" : 5,
"max_score" : 0.0,
"hits" : [ ]
},
"aggregations" : {
"grades_stats" : {
"count" : 5,
"min" : 46.5,
"max" : 81.4,
"avg" : 63.8,
"sum" : 319.0
}
}
}八、高级统计
高级统计还会返回方差、标准差等：
curl -XPOST "http://localhost:9200/books/_search?pretty" -d'
{
"size": 0,
"aggs": {
"grades_stats": {
"extended_stats": {
"field": "price"
}
}
}
}
'统计结果：
{
"took" : 3,
"timed_out" : false,
"_shards" : {
"total" : 5,
"successful" : 5,
"failed" : 0
},
"hits" : {
"total" : 5,
"max_score" : 0.0,
"hits" : [ ]
},
"aggregations" : {
"grades_stats" : {
"count" : 5,
"min" : 46.5,
"max" : 81.4,
"avg" : 63.8,
"sum" : 319.0,
"sum_of_squares" : 21095.46,
"variance" : 148.65199999999967,
"std_deviation" : 12.19229264740638,
"std_deviation_bounds" : {
"upper" : 88.18458529481276,
"lower" : 39.41541470518724
}
}
}
}九、百分比统计
curl -XPOST "http://localhost:9200/books/_search?pretty" -d '
{
"size": 0,
"aggs": {
"load_time_outlier": {
"percentiles": {
"field": "year"
}
}
}
}
'返回结果：
{
"took" : 3,
"timed_out" : false,
"_shards" : {
"total" : 5,
"successful" : 5,
"failed" : 0
},
"hits" : {
"total" : 5,
"max_score" : 0.0,
"hits" : [ ]
},
"aggregations" : {
"load_time_outlier" : {
"values" : {
"1.0" : 2007.2,
"5.0" : 2008.0000000000002,
"25.0" : 2012.0,
"50.0" : 2012.0,
"75.0" : 2014.0,
"95.0" : 2015.6000000000001,
"99.0" : 2015.92
}
}
}
}十、分段统计
统计价格小于50、50－80、大于80的百分比：
curl -XPOST "http://localhost:9200/books/_search?pretty" -d '{
"size": 0,
"aggs": {
"price_ranges": {
"range": {
"field": "price",
"ranges": [{
"to": 50
}, {
"from": 50,
"to": 80
}, {
"from": 80
}]
}
}
}
}
'返回结果：
{
"took" : 1,
"timed_out" : false,
"_shards" : {
"total" : 5,
"successful" : 5,
"failed" : 0
},
"hits" : {
"total" : 5,
"max_score" : 0.0,
"hits" : [ ]
},
"aggregations" : {
"price_ranges" : {
"buckets" : [ {
"key" : "*-50.0",
"to" : 50.0,
"to_as_string" : "50.0",
"doc_count" : 1
}, {
"key" : "50.0-80.0",
"from" : 50.0,
"from_as_string" : "50.0",
"to" : 80.0,
"to_as_string" : "80.0",
"doc_count" : 3
}, {
"key" : "80.0-*",
"from" : 80.0,
"from_as_string" : "80.0",
"doc_count" : 1
} ]
}
}
}
