During an infrastructure monitoring and incident response, you can dig deeper into the metrics and logs to find the cause. Explore also allows you to correlate metrics and logs by viewing them side-by-side. This creates a new debugging workflow:
1. Receive an alert.
1. Drill down and examine metrics.
1. Drill down again and search logs related to the metric and time interval (and in the future, distributed traces).
If the data source supports a full range log volume histogram, the graph with log distribution for all entered log queries is shown automatically. This feature is currently supported by Elasticsearch and Loki data sources.
**NOTE:** In Loki, this full range log volume histogram is rendered by metric query which can be expensive depending on time range queried. This query may be particularly challenging for smaller Loki installations to process. To mitigate this, we recommend using a proxy like [nginx](https://www.nginx.com/) in front of Loki to set a custom timeout (e.g. 10 seconds) for these queries. Log volume histogram queries can be identified by looking for queries with the HTTP header `X-Query-Tags` with value `Source=logvolhist`; these headers are added by Grafana to all log volume histogram queries.
If the data source does not support loading full range log volume histogram, the logs model computes a time series based on the log row counts bucketed by an automatically calculated time interval, and the first log row's timestamp then anchors the start of the histogram from the result. The end of the time series is anchored to the time picker's **To** range.
For logs where a level label is specified, we use the value of the label to determine the log level and update color accordingly. If the log doesn't have a level label specified, we try to find out if its content matches any of the supported expressions (see below for more information). The log level is always determined by the first match. In case Grafana is not able to determine a log level, it will be visualized with an unknown log level.
> **Tip:** If you use Loki data source and the "level" is in your log-line, use parsers (JSON, logfmt, regex,..) to extract the level information into a level label that is used to determine log level. This will allow the histogram to show the various log levels in separate bars.
Logs navigation next to the log lines can be used to request more logs. You can do this by clicking on Older logs button on the bottom of navigation. This is especially useful when you hit the line limit and you want to see more logs. Each request that is run from the navigation is then displayed in the navigation as separate page. Every page is showing from and to timestamp of the incoming log lines. You can see previous results by clicking on the page. Explore is caching last five requests run from the logs navigation, so you are not re-running the same queries when clicking on the pages.
Log data can be very repetitive and Explore can help by hiding duplicate log lines. There are a few different deduplication algorithms that you can use:
- **Exact -** Exact matches are done on the whole line except for date fields.
- **Numbers -** Matches on the line after stripping out numbers such as durations, IP addresses, and so on.
Each log row has an extendable area with its labels and detected fields, for more robust interaction. For all labels we have added the ability to filter for (positive filter) and filter out (negative filter) selected labels. Each field or label also has a stats icon to display ad-hoc statistics in relation to all displayed logs.
Explore automatically detects some incorrectly escaped sequences in log lines, such as newlines (`\n`, `\r`) or tabs (`\t`). When it detects such sequences, Explore provides an "Escape newlines" option.
To automatically fix incorrectly escaped sequences that Explore has detected:
1. Click "Escape newlines" to replace the sequences.
2. Manually review the replacements to confirm their correctness.
Explore replaces these sequences. When it does so, the option will change from "Escape newlines" to "Remove escaping". Evaluate the changes as the parsing may not be accurate based on the input received. You can revert the replacements by clicking "Remove escaping".
By using data links, you can turn any part of a log message into an internal or external link. The created link is visible as a button in the **Links** section inside the **Log details** view.
{{<figuresrc="/static/img/docs/explore/data-link-9-4.png"max-width="800px"caption="Data link in Explore">}}
As mentioned, one of the log integrations is for the new open source log aggregation system from Grafana Labs - [Loki](https://github.com/grafana/loki). Loki is designed to be very cost effective, as it does not index the contents of the logs, but rather a set of labels for each log stream. The logs from Loki are queried in a similar way to querying with label selectors in Prometheus. It uses labels to group log streams which can be made to match up with your Prometheus labels. For more information about Grafana Loki, refer to [Grafana Loki](https://github.com/grafana/loki) or the Grafana Labs hosted variant: [Grafana Cloud Logs](https://grafana.com/loki).
If you switch from a Prometheus query to a logs query (you can do a split first to have your metrics and logs side by side) then it will keep the labels from your query that exist in the logs and use those to query the log streams. For example, the following Prometheus query:
`grafana_alerting_active_alerts{job="grafana"}`
after switching to the Logs data source, the query changes to:
`{job="grafana"}`
This will return a chunk of logs in the selected time range that can be grepped/text searched.
If the selected data source implements logs sample, and supports both log and metric queries, then for metric queries you will be able to automatically see samples of log lines that contributed to visualized metrics. This feature is currently supported by Loki data sources.
Use the Live tailing feature to see real-time logs on supported data sources.
Click the **Live** button in the Explore toolbar to switch to Live tail view.
While in Live tail view new logs will come from the bottom of the screen and will have fading contrasting background so you can keep track of what is new. Click the **Pause** button or scroll the logs view to pause the Live tailing and explore previous logs without interruption. Click **Resume** button to resume the Live tailing or click **Stop** button to exit Live tailing and go back to standard Explore view.
