# Metrics Plugins

Apache Pinot uses a pluggable metrics factory to support multiple metrics backends. Each Pinot component (Server, Broker, Controller, Minion) can be independently configured with a metrics implementation.

## Available Implementations

| Plugin               | Class Name                                                             | Description                                                             |
| -------------------- | ---------------------------------------------------------------------- | ----------------------------------------------------------------------- |
| **Yammer** (default) | `org.apache.pinot.plugin.metrics.yammer.YammerMetricsFactory`          | Lightweight, default metrics implementation                             |
| **Dropwizard**       | `org.apache.pinot.plugin.metrics.dropwizard.DropwizardMetricsFactory`  | Full Dropwizard Metrics integration with sliding time window reservoirs |
| **Compound**         | `org.apache.pinot.plugin.metrics.compound.CompoundPinotMetricsFactory` | Registers metrics in multiple backends simultaneously                   |

## Configuration

Configure the metrics factory for any component using:

```properties
pinot.<component>.metrics.factory.className=<factory-class-name>
```

Where `<component>` is one of: `server`, `broker`, `controller`, `minion`.

### Yammer Metrics (Default)

The default metrics backend. No additional configuration required.

```properties
pinot.server.metrics.factory.className=org.apache.pinot.plugin.metrics.yammer.YammerMetricsFactory
```

### Dropwizard Metrics

Provides full Dropwizard Metrics library integration with sliding 15-minute time window reservoirs, detailed histograms and timers, and JMX reporting.

```properties
pinot.server.metrics.factory.className=org.apache.pinot.plugin.metrics.dropwizard.DropwizardMetricsFactory
```

**Additional properties:**

| Property                                      | Default                           | Description                 |
| --------------------------------------------- | --------------------------------- | --------------------------- |
| `pinot.<component>.metrics.dropwizard.domain` | `org.apache.pinot.common.metrics` | JMX domain name for metrics |

**Example:**

```properties
pinot.server.metrics.factory.className=org.apache.pinot.plugin.metrics.dropwizard.DropwizardMetricsFactory
pinot.server.metrics.dropwizard.domain=my.company.pinot.metrics
```

### Compound Metrics (Multi-Backend)

The Compound metrics plugin registers metrics in multiple backends simultaneously. This is useful for comparing metric implementations or reporting to multiple monitoring systems.

```properties
pinot.server.metrics.factory.className=org.apache.pinot.plugin.metrics.compound.CompoundPinotMetricsFactory
```

**Additional properties:**

| Property                                       | Default     | Description                                                                         |
| ---------------------------------------------- | ----------- | ----------------------------------------------------------------------------------- |
| `pinot.<component>.metrics.compound.algorithm` | `CLASSPATH` | Discovery algorithm: `CLASSPATH`, `SERVICE_LOADER`, or `LIST`                       |
| `pinot.<component>.metrics.compound.ignored`   | (empty)     | Comma-separated list of factory class names to exclude                              |
| `pinot.<component>.metrics.compound.list`      | (empty)     | Comma-separated list of factory class names to include (only with `algorithm=LIST`) |

**Example: Use both Yammer and Dropwizard:**

```properties
pinot.server.metrics.factory.className=org.apache.pinot.plugin.metrics.compound.CompoundPinotMetricsFactory
pinot.server.metrics.compound.algorithm=LIST
pinot.server.metrics.compound.list=org.apache.pinot.plugin.metrics.yammer.YammerMetricsFactory,org.apache.pinot.plugin.metrics.dropwizard.DropwizardMetricsFactory
```

**Example: Classpath discovery excluding Yammer:**

```properties
pinot.server.metrics.factory.className=org.apache.pinot.plugin.metrics.compound.CompoundPinotMetricsFactory
pinot.server.metrics.compound.algorithm=CLASSPATH
pinot.server.metrics.compound.ignored=org.apache.pinot.plugin.metrics.yammer.YammerMetricsFactory
```

{% hint style="warning" %}
When using Compound metrics, ensure JMX MBean names don't conflict between registries. Conflicting MBean names may cause unpredictable metric values.
{% endhint %}

## Metric Types

Pinot exposes the following metric primitives through all backends:

| Type          | Description            | Example                   |
| ------------- | ---------------------- | ------------------------- |
| **Counter**   | Discrete event counts  | Total queries processed   |
| **Meter**     | Event rates            | Queries per second        |
| **Timer**     | Latency and throughput | Query execution time      |
| **Histogram** | Value distributions    | Query result sizes        |
| **Gauge**     | Point-in-time values   | Segment count, heap usage |

## JMX Reporting

All metrics implementations include a JMX reporter enabled by default. The `JmxReporterMetricsRegistryRegistrationListener` is automatically registered when the metrics system initializes.

To configure additional metrics reporting (e.g., Prometheus, Grafana), see [Monitor Pinot Using Prometheus and Grafana](https://docs.pinot.apache.org/operate-pinot/monitoring/monitor-pinot-using-prometheus-and-grafana).