OpenSearch/docs/reference/ml/functions/sum.asciidoc

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[role="xpack"]
[[ml-sum-functions]]
=== Sum functions
The sum functions detect anomalies when the sum of a field in a bucket is anomalous.
If you want to monitor unusually high totals, use high-sided functions.
If want to look at drops in totals, use low-sided functions.
If your data is sparse, use `non_null_sum` functions. Buckets without values are
ignored; buckets with a zero value are analyzed.
The {ml-features} include the following sum functions:
* xref:ml-sum[`sum`, `high_sum`, `low_sum`]
* xref:ml-nonnull-sum[`non_null_sum`, `high_non_null_sum`, `low_non_null_sum`]
[float]
[[ml-sum]]
==== Sum, high_sum, low_sum
The `sum` function detects anomalies where the sum of a field in a bucket is
anomalous.
If you want to monitor unusually high sum values, use the `high_sum` function.
If you want to monitor unusually low sum values, use the `low_sum` function.
These functions support the following properties:
* `field_name` (required)
* `by_field_name` (optional)
* `over_field_name` (optional)
* `partition_field_name` (optional)
For more information about those properties, see
{ref}/ml-job-resource.html#ml-detectorconfig[Detector Configuration Objects].
.Example 1: Analyzing total expenses with the sum function
[source,js]
--------------------------------------------------
{
"function" : "sum",
"field_name" : "expenses",
"by_field_name" : "costcenter",
"over_field_name" : "employee"
}
--------------------------------------------------
// NOTCONSOLE
If you use this `sum` function in a detector in your job, it
models total expenses per employees for each cost center. For each time bucket,
it detects when an employees expenses are unusual for a cost center compared
to other employees.
.Example 2: Analyzing total bytes with the high_sum function
[source,js]
--------------------------------------------------
{
"function" : "high_sum",
"field_name" : "cs_bytes",
"over_field_name" : "cs_host"
}
--------------------------------------------------
// NOTCONSOLE
If you use this `high_sum` function in a detector in your job, it
models total `cs_bytes`. It detects `cs_hosts` that transfer unusually high
volumes compared to other `cs_hosts`. This example looks for volumes of data
transferred from a client to a server on the internet that are unusual compared
to other clients. This scenario could be useful to detect data exfiltration or
to find users that are abusing internet privileges.
[float]
[[ml-nonnull-sum]]
==== Non_null_sum, high_non_null_sum, low_non_null_sum
The `non_null_sum` function is useful if your data is sparse. Buckets without
values are ignored and buckets with a zero value are analyzed.
If you want to monitor unusually high totals, use the `high_non_null_sum`
function.
If you want to look at drops in totals, use the `low_non_null_sum` function.
These functions support the following properties:
* `field_name` (required)
* `by_field_name` (optional)
* `partition_field_name` (optional)
For more information about those properties, see
{ref}/ml-job-resource.html#ml-detectorconfig[Detector Configuration Objects].
NOTE: Population analysis (that is to say, use of the `over_field_name` property)
is not applicable for this function.
.Example 3: Analyzing employee approvals with the high_non_null_sum function
[source,js]
--------------------------------------------------
{
"function" : "high_non_null_sum",
"fieldName" : "amount_approved",
"byFieldName" : "employee"
}
--------------------------------------------------
// NOTCONSOLE
If you use this `high_non_null_sum` function in a detector in your job, it
models the total `amount_approved` for each employee. It ignores any buckets
where the amount is null. It detects employees who approve unusually high
amounts compared to their past behavior.
//For this credit control system analysis, using non_null_sum will ignore
//periods where the employees are not active on the system.