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* moved some content into other topics * Update variable-value-tags.md * Update variable-selection-options.md * Update add-query-variable.md * Update templates-and-variables.md * Create add-custom-variable.md * Update menu.yaml * Update templates-and-variables.md * Update templates-and-variables.md * editing content * Create add-text-box-variable.md * added links * content updates * update-content * Update templates-and-variables.md * Update menu.yaml * Update add-constant-variable.md * Update add-constant-variable.md * Update docs/sources/variables/add-query-variable.md Co-authored-by: Arve Knudsen <arve.knudsen@gmail.com> * Update docs/sources/variables/variable-value-tags.md Co-authored-by: Arve Knudsen <arve.knudsen@gmail.com> * Update docs/sources/variables/variable-value-tags.md Co-authored-by: Arve Knudsen <arve.knudsen@gmail.com> * Update docs/sources/variables/variable-value-tags.md Co-authored-by: Arve Knudsen <arve.knudsen@gmail.com> Co-authored-by: Arve Knudsen <arve.knudsen@gmail.com>
46 lines
3.5 KiB
Markdown
46 lines
3.5 KiB
Markdown
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title = "Add a query variable"
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type = "docs"
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[menu.docs]
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weight = 500
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# Add a query variable
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Query variables allow you to write a data source query that can return a list of metric names, tag values, or keys. For example, a query variable might return a list of server names, sensor IDs, or data centers. The variable values change as they dynamically fetch options with a data source query.
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Query expressions can contain references to other variables and in effect create linked variables. Grafana detects this and automatically refreshes a variable when one of its linked variables change.
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## Query expressions
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Query expressions are different for each data source. For more information, refer to the documentation for your [data source]({{< relref "../features/datasources/_index.md" >}}).
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## Enter General options
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1. Navigate to the dashboard you want to make a variable for and then click the **Dashboard settings** (gear) icon at the top of the page.
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1. On the Variables tab, click **New**.
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1. Enter a **Name** for your variable.
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1. In the **Type** list, select **Query**.
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1. (optional) In **Label**, enter the display name of the variable dropdown. If you don't enter a display name, then the dropdown label will be the variable name.
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1. Choose a **Hide** option:
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- **No selection (blank) -** The variable dropdown displays the variable **Name** or **Label** value. This is the default.
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- **Label -** The variable dropdown only displays the selected variable value and a down arrow.
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- **Variable -** No variable dropdown is displayed on the dashboard.
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## Enter Query Options
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1. In the **Data source** list, select the target data source for the query. For more information about data sources, refer to [Add a data source]({{< relref "../features/datasources/add-a-data-source.md" >}}).
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1. In the **Refresh** list, select when the variable should update options.
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- **Never -** Variables queries are cached and values are not updated. This is fine if the values never change, but problematic if they are dynamic and change a lot.
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- **On Dashboard Load -** Queries the data source every time the dashboard loads. This slows down dashboard loading, because the variable query needs to be completed before dashboard can be initialized.
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- **On Time Range Change -** Queries the data source when the dashboard time range changes. Only use this option if your variable options query contains a time range filter or is dependent on the dashboard time range.
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1. In the **Query** field, enter a query.
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- The query field varies according to your data source. Some data sources have custom query editors.
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- If you need more room in a single input field query editor, then hover your cursor over the lines in the lower right corner of the field and drag downward to expand.
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1. (optional) In the **Regex** field, type a regex expression to filter or capture specific parts of the names returned by your data source query. To see examples, refer to [Filter variables with regex]({{< relref "filter-variables-with-regex.md" >}}).
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1. In the **Sort** list, select the sort order for values to be displayed in the dropdown list. The default option, **Disabled**, means that the order of options returned by your data source query will be used.
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1. (optional) Enter [Selection Options]({{< relref "variable-selection-options.md" >}}).
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1. (optional) Enter [Value groups/tags]({{< relref "variable-value-tags.md" >}}).
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1. In **Preview of values**, Grafana displays a list of the current variable values. Review them to ensure they match what you expect.
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1. Click **Add** to add the variable to the dashboard.
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