extend operator
Applies to: ✅ Microsoft Fabric ✅ Azure Data Explorer ✅ Azure Monitor ✅ Microsoft Sentinel
Creates calculated columns and append them to the result set.
Syntax
T | extend [ColumnName | (ColumnName[, ...]) =] Expression [, ...]
Learn more about syntax conventions.
Parameters
| Name | Type | Required | Description |
|---|---|---|---|
| T | string |
✔️ | Tabular input to extend. |
| ColumnName | string |
Name of the column to add or update. | |
| Expression | string |
✔️ | Calculation to perform over the input. |
- If ColumnName is omitted, the output column name of Expression is automatically generated.
- If Expression returns more than one column, a list of column names can be specified in parentheses. Then, Expression's output columns is given the specified names. If a list of the column names isn't specified, all Expression's output columns with generated names are added to the output.
Returns
A copy of the input tabular result set, such that:
- Column names noted by
extendthat already exist in the input are removed and appended as their new calculated values. - Column names noted by
extendthat don't exist in the input are appended as their new calculated values.
Note
The extend operator adds a new column to the input result set, which does
not have an index. In most cases, if the new column is set to be exactly
the same as an existing table column that has an index, Kusto can automatically
use the existing index. However, in some complex scenarios this propagation is
not done. In such cases, if the goal is to rename a column, use the project-rename operator instead.
Example
StormEvents
| project EndTime, StartTime
| extend Duration = EndTime - StartTime
The following table shows only the first 10 results. To see the full output, run the query.
| EndTime | StartTime | Duration |
|---|---|---|
| 2007-01-01T00:00:00Z | 2007-01-01T00:00:00Z | 00:00:00 |
| 2007-01-01T00:25:00Z | 2007-01-01T00:25:00Z | 00:00:00 |
| 2007-01-01T02:24:00Z | 2007-01-01T02:24:00Z | 00:00:00 |
| 2007-01-01T03:45:00Z | 2007-01-01T03:45:00Z | 00:00:00 |
| 2007-01-01T04:35:00Z | 2007-01-01T04:35:00Z | 00:00:00 |
| 2007-01-01T04:37:00Z | 2007-01-01T03:37:00Z | 01:00:00 |
| 2007-01-01T05:00:00Z | 2007-01-01T00:00:00Z | 05:00:00 |
| 2007-01-01T05:00:00Z | 2007-01-01T00:00:00Z | 05:00:00 |
| 2007-01-01T06:00:00Z | 2007-01-01T00:00:00Z | 06:00:00 |
| 2007-01-01T06:00:00Z | 2007-01-01T00:00:00Z | 06:00:00 |
Related content
- Use series_stats to return multiple columns