# How Do I Write an "Or" Logical Operator on Prometheus or Grafana

In Prometheus and Grafana, you can implement an "OR" logical operation using the `or` operator in Prometheus Query Language (PromQL) or by structuring queries appropriately in Grafana. Here’s how to use the "OR" operator effectively in both contexts.

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### Using the `or` Operator in PromQL

The `or` operator allows you to combine multiple metrics or expressions. When either condition is true, the combined result will be true.

### Syntax

```
metric1 or metric2
```

### Example 1: Basic Usage of `or`

Assuming you have two metrics, `http_requests_total{status="200"}` and `http_requests_total{status="500"}`, and you want to retrieve data where either status is present:

```
http_requests_total{status="200"} or http_requests_total{status="500"}
```

This query will return results for both the 200 and 500 HTTP status codes.

### Example 2: Combining Metrics with `or`

You can also use the `or` operator to combine different metrics. For example, if you have a metric for HTTP requests and another for error rates:

```
http_requests_total or http_errors_total
```

This will return data from both metrics where either exists.

### Step 2: Using the `or` Operator in Grafana

When writing queries in Grafana using Prometheus as a data source, you can use the `or` operator in the query editor just as you would in a standard Prometheus query.

1. Open your Grafana dashboard and add a new panel.
2. In the query editor, enter your PromQL expression using the `or` operator.
3. Execute the query to see the combined results.

### Example in Grafana

If you want to visualize requests or errors, you can input:

```
sum(rate(http_requests_total[5m])) or sum(rate(http_errors_total[5m]))
```

This query would provide a time series showing either the rate of requests or the rate of errors over the last 5 minutes.

### Considerations

- **Label Matching**: When using `or`, ensure that the metrics being combined share relevant labels if you expect to compare them directly. Mismatched labels may result in empty results.
- **Result Handling**: The result of an `or` operation will be a vector that combines the matching time series, which can be useful for comparisons or aggregations in Grafana visualizations.


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