The Loki data source's query editor helps you create [log]({{< relref "#create-a-log-query" >}}) and [metric]({{< relref "#create-a-metric-query" >}}) queries that use Loki's query language, [LogQL](/docs/loki/latest/logql/).
This topic explains querying specific to the Loki data source.
For general documentation on querying data sources in Grafana, see [Query and transform data]({{< relref "../../../panels-visualizations/query-transform-data" >}}).
## Choose a query editing mode
You can switch the Loki query editor between two modes:
- [Code mode]({{< relref "#code-mode" >}}), which provides a feature-rich editor for writing queries
- [Builder mode]({{< relref "#builder-mode" >}}), which provides a visual query designer
To switch between the editor modes, select the corresponding **Builder** and **Code** tabs.
To run a query, select **Run queries** located at the top of the editor.
Each mode is synchronized with the other modes, so you can switch between them without losing your work, although there are some limitations.
Builder mode doesn't yet support some complex queries.
When you switch from Code mode to Builder mode with such a query, the editor displays a popup that explains how you might lose parts of the query if you continue.
You can then decide whether you still want to switch to Builder mode.
You can also augment queries by using [template variables]({{< relref "./template-variables/" >}}).
## Code mode
In **Code mode**, you can write complex queries using a text editor with autocompletion features and syntax highlighting.
| {{<figuresrc="/static/img/docs/v95/loki_operation_replace.png"class="docs-image--no-shadow"max-width="30px">}} | Replaces the operation with different operation of the same type. |
| {{<figuresrc="/static/img/docs/v95/loki_operation_description.png"class="docs-image--no-shadow"max-width="30px">}} | Opens the operation's description tooltip. |
| {{<figuresrc="/static/img/docs/v95/loki_operation_remove.png"class="docs-image--no-shadow"max-width="30px">}} | Removes the operation. |
Some operations have additional parameters under the operation header.
For details about each operation, use the `info` button to view the operation's description, or refer to the [Loki documentation](/docs/loki/latest/operations/).
Some operations make sense only when used in a specific order.
If adding an operation would result in nonsensical query, the query editor adds the operation to the correct place.
To re-order operations manually, drag the operation box by its name and drop it into the desired place.
#### Hints
In same cases the query editor can detect which operations would be most appropriate for a selected log stream. In such cases it will show a hint next to the `+ Operations` button. Click on the hint to add the operations to your query.
## Create a log query
Loki log queries return the contents of the log lines.
You can query and display log data from Loki via [Explore]({{< relref "../../../explore" >}}), and with the [Logs panel]({{< relref "../../../panels-visualizations/visualizations/logs" >}}) in dashboards.
To display the results of a log query, select the Loki data source, then enter a LogQL query.
For more information about log queries and LogQL, refer to the [Loki log queries documentation](/docs/loki/latest/logql/log_queries/).
In Explore, you can can retrieve the context surrounding your log results by clicking the `Show Context` button. You'll be able to investigate the logs from the same log stream that came before and after the log message you're interested in.
The initial log context query is created from all labels defining the stream for the selected log line. You can use the log context query editor to widen the search by removing one or more of the label filters from log stream. Additionally, if you used a parser in your original query, you can refine your search by using extracted labels filters.
To reduce the repetition of selecting and removing the same labels when examining multiple log context windows, Grafana stores your selected labels and applies them to each open context window. This lets you seamlessly navigate through various log context windows without having to reapply your filters.
To reset filters and use the initial log context query, click the `Revert to initial query` button next to the query preview.
This example provides a basic NGINX proxy configuration.
It assumes that the Grafana server is available at `http://localhost:3000/`, the Loki server is running locally without proxy, and your external site uses HTTPS.
If you also host Loki behind an NGINX proxy, repeat the following configuration for Loki.
In the `http` section of NGINX configuration, add the following map definition:
```
map $http_upgrade $connection_upgrade {
default upgrade;
'' close;
}
```
In your `server` section, add the following configuration:
1. Select the **Show logs** button to display log lines based on the selected labels, or select the **Show logs rate** button to show the rate based on metrics such as requests per second. Additionally, you can validate the selector by clicking the **Validate selector** button.
This section is only shown if the `Explain query` switch from the query editor top toolbar is set to `on`. It shows a step by step explanation of all query parts and the operations.
| **Type** | Selects the query type to run. The `instant` type queries against a single point in time. We use the "To" time from the time range. The `range` type queries over the selected range of time. |
| **Line limit** | Defines the upper limit for the number of log lines returned by a query. The default is Loki's configured maximum lines limit. |
| **Legend** | _(Available only in a dashboard)_ Controls the time series name, using a name or pattern. For example, `{{hostname}}` is replaced with the label value for the label `hostname`. |
| **Step** | Sets the step parameter of Loki metrics queries. The default value equals to the value of `$__interval` variable, which is calculated using the time range and the width of the graph (the number of pixels). |
| **Resolution** | Deprecated. Sets the step parameter of Loki metrics range queries. With a resolution of `1/1`, each pixel corresponds to one data point. `1/2` retrieves one data point for every other pixel, `1/10` retrieves one data point per 10 pixels, and so on. Lower resolutions perform better. |
