最大值聚合
编辑最大值聚合编辑
一种 单值 指标聚合，用于跟踪并返回从聚合文档中提取的数值中的最大值。
min 和 max 聚合对数据的 double 表示形式进行操作。因此，当对绝对值大于 2^53 的长整型进行运算时，结果可能近似。
计算所有文档中的最高价格值
response = client.search(
index: 'sales',
size: 0,
body: {
aggregations: {
max_price: {
max: {
field: 'price'
}
}
}
}
)
puts response
POST /sales/_search?size=0
{
"aggs": {
"max_price": { "max": { "field": "price" } }
}
}
响应
{
...
"aggregations": {
"max_price": {
"value": 200.0
}
}
}
可以看出，聚合的名称（上面的 max_price）也用作从返回的响应中检索聚合结果的键。
脚本编辑
如果需要获取比单个字段更复杂的 max，请对 运行时字段 运行聚合。
response = client.search(
index: 'sales',
body: {
size: 0,
runtime_mappings: {
'price.adjusted' => {
type: 'double',
script: "\n double price = doc['price'].value;\n if (doc['promoted'].value) {\n price *= 0.8;\n }\n emit(price);\n "
}
},
aggregations: {
max_price: {
max: {
field: 'price.adjusted'
}
}
}
}
)
puts response
POST /sales/_search
{
"size": 0,
"runtime_mappings": {
"price.adjusted": {
"type": "double",
"script": """
double price = doc['price'].value;
if (doc['promoted'].value) {
price *= 0.8;
}
emit(price);
"""
}
},
"aggs": {
"max_price": {
"max": { "field": "price.adjusted" }
}
}
}
缺失值编辑
missing 参数定义了如何处理缺少值的文档。默认情况下，它们将被忽略，但也可以将它们视为具有值。
response = client.search(
index: 'sales',
body: {
aggregations: {
grade_max: {
max: {
field: 'grade',
missing: 10
}
}
}
}
)
puts response
直方图字段编辑
当对 直方图字段 计算 max 时，聚合的结果是 values 数组中所有元素的最大值。请注意，直方图的 counts 数组将被忽略。
例如，对于以下存储了不同网络的延迟指标的预聚合直方图的索引
response = client.indices.create(
index: 'metrics_index',
body: {
mappings: {
properties: {
latency_histo: {
type: 'histogram'
}
}
}
}
)
puts response
response = client.index(
index: 'metrics_index',
id: 1,
refresh: true,
body: {
'network.name' => 'net-1',
latency_histo: {
values: [
0.1,
0.2,
0.3,
0.4,
0.5
],
counts: [
3,
7,
23,
12,
6
]
}
}
)
puts response
response = client.index(
index: 'metrics_index',
id: 2,
refresh: true,
body: {
'network.name' => 'net-2',
latency_histo: {
values: [
0.1,
0.2,
0.3,
0.4,
0.5
],
counts: [
8,
17,
8,
7,
6
]
}
}
)
puts response
response = client.search(
index: 'metrics_index',
size: 0,
filter_path: 'aggregations',
body: {
aggregations: {
max_latency: {
max: {
field: 'latency_histo'
}
}
}
}
)
puts response
PUT metrics_index
{
"mappings": {
"properties": {
"latency_histo": { "type": "histogram" }
}
}
}
PUT metrics_index/_doc/1?refresh
{
"network.name" : "net-1",
"latency_histo" : {
"values" : [0.1, 0.2, 0.3, 0.4, 0.5],
"counts" : [3, 7, 23, 12, 6]
}
}
PUT metrics_index/_doc/2?refresh
{
"network.name" : "net-2",
"latency_histo" : {
"values" : [0.1, 0.2, 0.3, 0.4, 0.5],
"counts" : [8, 17, 8, 7, 6]
}
}
POST /metrics_index/_search?size=0&filter_path=aggregations
{
"aggs" : {
"max_latency" : { "max" : { "field" : "latency_histo" } }
}
}
max 聚合将返回所有直方图字段的最大值
{
"aggregations": {
"max_latency": {
"value": 0.5
}
}
}