ElasticSearch 聚合嵌套查询

Posted 2020-12-05 chenyifan

第一个分析需求：计算每个tag下的商品数量

GET /ecommerce/product/_search
{
"aggs": {
"group_by_tags": {
"terms": { "field": "tags" }
}
}
}

将文本field的fielddata属性设置为true

PUT /ecommerce/_mapping/product
{
"properties": {
"tags": {
"type": "text",
"fielddata": true
}
}
}

GET /ecommerce/product/_search
{
"size": 0,
"aggs": {
"all_tags": {
"terms": { "field": "tags" }
}
}
}

{
"took": 20,
"timed_out": false,
"_shards": {
"total": 5,
"successful": 5,
"failed": 0
},
"hits": {
"total": 4,
"max_score": 0,
"hits": []
},
"aggregations": {
"group_by_tags": {
"doc_count_error_upper_bound": 0,
"sum_other_doc_count": 0,
"buckets": [
{
"key": "fangzhu",
"doc_count": 2
},
{
"key": "meibai",
"doc_count": 2
},
{
"key": "qingxin",
"doc_count": 1
}
]
}
}
}

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第二个聚合分析的需求：对名称中包含yagao的商品，计算每个tag下的商品数量

GET /ecommerce/product/_search
{
"size": 0,
"query": {
"match": {
"name": "yagao"
}
},
"aggs": {
"all_tags": {
"terms": {
"field": "tags"
}
}
}
}

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第三个聚合分析的需求：先分组，再算每组的平均值，计算每个tag下的商品的平均价格

GET /ecommerce/product/_search
{
"size": 0,
"aggs" : {
"group_by_tags" : {
"terms" : { "field" : "tags" },
"aggs" : {
"avg_price" : {
"avg" : { "field" : "price" }
}
}
}
}
}

{
"took": 8,
"timed_out": false,
"_shards": {
"total": 5,
"successful": 5,
"failed": 0
},
"hits": {
"total": 4,
"max_score": 0,
"hits": []
},
"aggregations": {
"group_by_tags": {
"doc_count_error_upper_bound": 0,
"sum_other_doc_count": 0,
"buckets": [
{
"key": "fangzhu",
"doc_count": 2,
"avg_price": {
"value": 27.5
}
},
{
"key": "meibai",
"doc_count": 2,
"avg_price": {
"value": 40
}
},
{
"key": "qingxin",
"doc_count": 1,
"avg_price": {
"value": 40
}
}
]
}
}
}

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第四个数据分析需求：计算每个tag下的商品的平均价格，并且按照平均价格降序排序

GET /ecommerce/product/_search
{
"size": 0,
"aggs" : {
"all_tags" : {
"terms" : { "field" : "tags", "order": { "avg_price": "desc" } },
"aggs" : {
"avg_price" : {
"avg" : { "field" : "price" }
}
}
}
}
}

我们现在全部都是用es的restful api在学习和讲解es的所欲知识点和功能点，但是没有使用一些编程语言去讲解（比如java），原因有以下：

1、es最重要的api，让我们进行各种尝试、学习甚至在某些环境下进行使用的api，就是restful api。如果你学习不用es restful api，比如我上来就用java api来讲es，也是可以的，但是你根本就漏掉了es知识的一大块，你都不知道它最重要的restful api是怎么用的
2、讲知识点，用es restful api，更加方便，快捷，不用每次都写大量的java代码，能加快讲课的效率和速度，更加易于同学们关注es本身的知识和功能的学习
3、我们通常会讲完es知识点后，开始详细讲解java api，如何用java api执行各种操作
4、我们每个篇章都会搭配一个项目实战，项目实战是完全基于java去开发的真实项目和系统

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第五个数据分析需求：按照指定的价格范围区间进行分组，然后在每组内再按照tag进行分组，最后再计算每组的平均价格

GET /ecommerce/product/_search
{
"size": 0,
"aggs": {
"group_by_price": {
"range": {
"field": "price",
"ranges": [
{
"from": 0,
"to": 20
},
{
"from": 20,
"to": 40
},
{
"from": 40,
"to": 50
}
]
},
"aggs": {
"group_by_tags": {
"terms": {
"field": "tags"
},
"aggs": {
"average_price": {
"avg": {
"field": "price"
}
}
}
}
}
}
}
}