---
title: Telegraf aggregator and processor plugins
description: Aggregator and processor plugins work between the input plugins and output plugins to aggregate and process metrics in Telegraf.
menu:
  telegraf_1_19:
    name: Aggregator & processor plugins
    weight: 20
    parent: Concepts
---

Besides the input plugins and output plugins, Telegraf includes aggregator and processor plugins, which are used to aggregate and process metrics as they pass through Telegraf.

{{< diagram >}}
  graph TD
  Process[Process<br/> - transform<br/> - decorate<br/> - filter]
  Aggregate[Aggregate<br/> - transform<br/> - decorate<br/> - filter]

  CPU --> Process
  Memory --> Process
  MySQL --> Process
  SNMP --> Process
  Docker --> Process
  Process --> Aggregate
  Aggregate --> InfluxDB
  Aggregate --> File
  Aggregate --> Kafka

style Process text-align:left
style Aggregate text-align:left
{{< /diagram >}}

**Processor plugins** process metrics as they pass through and immediately emit
results based on the values they process. For example, this could be printing
all metrics or adding a tag to all metrics that pass through.

**Aggregator plugins**, on the other hand, are a bit more complicated. Aggregators
are typically for emitting new _aggregate_ metrics, such as a running mean,
minimum, maximum, quantiles, or standard deviation. For this reason, all _aggregator_
plugins are configured with a `period`. The `period` is the size of the window
of metrics that each _aggregate_ represents. In other words, the emitted
_aggregate_ metric will be the aggregated value of the past `period` seconds.
Since many users will only care about their aggregates and not every single metric
gathered, there is also a `drop_original` argument, which tells Telegraf to only
emit the aggregates and not the original metrics.

{{% note %}}
#### Behavior of processors and aggregators when used together
When using both aggregator and processor plugins in Telegraf v1.17, processor plugins
process data and then pass it to aggregator plugins.
After aggregator plugins aggregate the data, they pass it back to processor plugins.
This can have unintended consequences, such as executing mathematical operations twice.
_See [influxdata/telegraf#7993](https://github.com/influxdata/telegraf/issues/7993)._

If using custom processor scripts, they must be idempotent (repeatable, without side-effects).
For custom processes that are not idempotent, use [namepass or namedrop](/telegraf/v1.17/administration/configuration/#input-config-namepass-and-namedrop) to avoid issues when aggregated data is processed a second time.
{{% /note %}}