Value count aggregation
A single-value metrics aggregation that counts the number of values that are extracted from the aggregated documents. These values can be extracted either from specific fields in the documents, or be generated by a provided script. Typically, this aggregator will be used in conjunction with other single-value aggregations. For example, when computing the avg one might be interested in the number of values the average is computed over.
value_count does not de-duplicate values, so even if a field has duplicates each value will be counted individually.
resp = client.search(
index="sales",
size="0",
aggs={
"types_count": {
"value_count": {
"field": "type"
}
}
},
)
print(resp) response = client.search(
index: 'sales',
size: 0,
body: {
aggregations: {
types_count: {
value_count: {
field: 'type'
}
}
}
}
)
puts response res, err := es.Search(
es.Search.WithIndex("sales"),
es.Search.WithBody(strings.NewReader(`{
"aggs": {
"types_count": {
"value_count": {
"field": "type"
}
}
}
}`)),
es.Search.WithSize(0),
es.Search.WithPretty(),
)
fmt.Println(res, err) const response = await client.search({
index: "sales",
size: 0,
aggs: {
types_count: {
value_count: {
field: "type",
},
},
},
});
console.log(response); POST /sales/_search?size=0
{
"aggs" : {
"types_count" : { "value_count" : { "field" : "type" } }
}
} Response:
{
...
"aggregations": {
"types_count": {
"value": 7
}
}
} The name of the aggregation (types_count above) also serves as the key by which the aggregation result can be retrieved from the returned response.
Script
If you need to count something more complex than the values in a single field you should run the aggregation on a runtime field.
resp = client.search(
index="sales",
size=0,
runtime_mappings={
"tags": {
"type": "keyword",
"script": "\n emit(doc['type'].value);\n if (doc['promoted'].value) {\n emit('hot');\n }\n "
}
},
aggs={
"tags_count": {
"value_count": {
"field": "tags"
}
}
},
)
print(resp) response = client.search(
index: 'sales',
body: {
size: 0,
runtime_mappings: {
tags: {
type: 'keyword',
script: "\n emit(doc['type'].value);\n if (doc['promoted'].value) {\n emit('hot');\n }\n "
}
},
aggregations: {
tags_count: {
value_count: {
field: 'tags'
}
}
}
}
)
puts response const response = await client.search({
index: "sales",
size: 0,
runtime_mappings: {
tags: {
type: "keyword",
script:
"\n emit(doc['type'].value);\n if (doc['promoted'].value) {\n emit('hot');\n }\n ",
},
},
aggs: {
tags_count: {
value_count: {
field: "tags",
},
},
},
});
console.log(response); POST /sales/_search
{
"size": 0,
"runtime_mappings": {
"tags": {
"type": "keyword",
"script": """
emit(doc['type'].value);
if (doc['promoted'].value) {
emit('hot');
}
"""
}
},
"aggs": {
"tags_count": {
"value_count": {
"field": "tags"
}
}
}
} Histogram fields
When the value_count aggregation is computed on histogram fields, the result of the aggregation is the sum of all numbers in the counts array of the histogram.
For example, for the following index that stores pre-aggregated histograms with latency metrics for different networks:
resp = client.index(
index="metrics_index",
id="1",
document={
"network.name": "net-1",
"latency_histo": {
"values": [
0.1,
0.2,
0.3,
0.4,
0.5
],
"counts": [
3,
7,
23,
12,
6
]
}
},
)
print(resp)
resp1 = client.index(
index="metrics_index",
id="2",
document={
"network.name": "net-2",
"latency_histo": {
"values": [
0.1,
0.2,
0.3,
0.4,
0.5
],
"counts": [
8,
17,
8,
7,
6
]
}
},
)
print(resp1)
resp2 = client.search(
index="metrics_index",
size="0",
aggs={
"total_requests": {
"value_count": {
"field": "latency_histo"
}
}
},
)
print(resp2) response = client.index(
index: 'metrics_index',
id: 1,
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,
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,
body: {
aggregations: {
total_requests: {
value_count: {
field: 'latency_histo'
}
}
}
}
)
puts response {
res, err := es.Index(
"metrics_index",
strings.NewReader(`{
"network.name": "net-1",
"latency_histo": {
"values": [
0.1,
0.2,
0.3,
0.4,
0.5
],
"counts": [
3,
7,
23,
12,
6
]
}
}`),
es.Index.WithDocumentID("1"),
es.Index.WithPretty(),
)
fmt.Println(res, err)
}
{
res, err := es.Index(
"metrics_index",
strings.NewReader(`{
"network.name": "net-2",
"latency_histo": {
"values": [
0.1,
0.2,
0.3,
0.4,
0.5
],
"counts": [
8,
17,
8,
7,
6
]
}
}`),
es.Index.WithDocumentID("2"),
es.Index.WithPretty(),
)
fmt.Println(res, err)
}
{
res, err := es.Search(
es.Search.WithIndex("metrics_index"),
es.Search.WithBody(strings.NewReader(`{
"aggs": {
"total_requests": {
"value_count": {
"field": "latency_histo"
}
}
}
}`)),
es.Search.WithSize(0),
es.Search.WithPretty(),
)
fmt.Println(res, err)
} const response = await client.index({
index: "metrics_index",
id: 1,
document: {
"network.name": "net-1",
latency_histo: {
values: [0.1, 0.2, 0.3, 0.4, 0.5],
counts: [3, 7, 23, 12, 6],
},
},
});
console.log(response);
const response1 = await client.index({
index: "metrics_index",
id: 2,
document: {
"network.name": "net-2",
latency_histo: {
values: [0.1, 0.2, 0.3, 0.4, 0.5],
counts: [8, 17, 8, 7, 6],
},
},
});
console.log(response1);
const response2 = await client.search({
index: "metrics_index",
size: 0,
aggs: {
total_requests: {
value_count: {
field: "latency_histo",
},
},
},
});
console.log(response2); PUT metrics_index/_doc/1
{
"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
{
"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
{
"aggs": {
"total_requests": {
"value_count": { "field": "latency_histo" }
}
}
} For each histogram field the value_count aggregation will sum all numbers in the counts array <1>. Eventually, it will add all values for all histograms and return the following result:
{
...
"aggregations": {
"total_requests": {
"value": 97
}
}
}
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https://www.elastic.co/guide/en/elasticsearch/reference/8.17/search-aggregations-metrics-valuecount-aggregation.html
