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learn-build-service-prod merged 4 commits into from
Sep 14, 2025
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Repo sync for protected branch #2730

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e36f23f
Updated mv-apply example
Sep 14, 2025
4e93111
Merge pull request #7092 from dyadav7/user/deepyadav/mv_apply_example
prmerger-automator[bot] Sep 14, 2025
03bd661
Merge pull request #7093 from MicrosoftDocs/main
learn-build-service-prod[bot] Sep 14, 2025
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Merging changes synced from https://github.com/MicrosoftDocs/dataexpl…
Sep 14, 2025
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84 changes: 59 additions & 25 deletions data-explorer/kusto/query/mv-apply-operator.md
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Expand Up @@ -96,61 +96,95 @@ Where *ItemIndex* has the syntax:

Review the examples and run them in your Data Explorer query page.

### Internal mv-expand done by mv-apply

The query helps in understanding the mv-expand done internally by mv-apply

:::moniker range="azure-data-explorer"
> [!div class="nextstepaction"]
> <a href="https://dataexplorer.azure.com/clusters/help/databases/Samples?query=H4sIAAAAAAAAA02MwQrCMBBE7%2FmKOSYQIfGgUOnB7yg9rCZKME1CWYoBP940IDiHWeYtvOgZjpgw9sN0ix4yJOffA0Jijeu6DnA10RLuSkwCLUb%2FiJzOs9Id2j940rBtt5%2BYL2I3iw%2BW7UClxLorj2MrcAbX4vNDxpyeCjmhq2TvFqaXhzWmb%2FUFxRAwu60AAAA%3D" target="_blank">Run the query</a>
::: moniker-end

```kusto
let data = datatable (index: int, Arr: dynamic)
[
0, dynamic([7]),
1, dynamic([6, 11, 7])
];
data
| mv-apply Arr2=Arr to typeof(long) on
(
take 100
)
```

**Output**

| index | Arr | Arr2 |
|--|--|--|
| 0 | [7] | 7 |
| 1 | [6, 11, 7] | 6 |
| 1 | [6, 11, 7] | 11|
| 1 | [6, 11, 7] | 7 |

### Getting the largest element from the array

The query outputs the smallest even number (2) and the smallest odd number (1).
<!-- //the query and header do not match. Is the query wrong?// -->
The query creates a new column having the largest element of an array.

:::moniker range="azure-data-explorer"
> [!div class="nextstepaction"]
> <a href="https://dataexplorer.azure.com/clusters/help/databases/Samples?query=H4sIAAAAAAAAAy2NsQrDMBBD93yFlkIydEimQvEn9BuCSy4h9M5nkmuxSz6+jqkGDRJ6YjKMkzcP16Bo82EhJMybCnqY4obdKKKv9YH9LeK39UtgJ/5FI6+7tanDMyM9dBrgyvyC4d5UbnNAPlcfI2cQk1AwxyfXciSdW9awdNCAym+rm5a/E/gf1LD7ASAFbUCrAAAA" target="_blank">Run the query</a>
> <a href="https://dataexplorer.azure.com/clusters/help/databases/Samples?query=H4sIAAAAAAAAA02NwQoCMQxE7%2F2KObZQwSoirOzBg1%2Bx9NC1VQrdtixBLPjx1oBiDkmYN8mkQPCOHEYe5OYUIGP24TkgZtI4r%2BsA37Jb4lWJSaDXVn8VORmNg8beKs3I%2FKPu2zE%2BWiXsSXwixAvLY%2BNqTQ1U6iWFZewZfQe1GspNppLvCiWDH0ru3QmD%2BXfConoD3WN%2F8L4AAAA%3D" target="_blank">Run the query</a>
::: moniker-end

```kusto
let _data =
range x from 1 to 8 step 1
| summarize l=make_list(x) by xMod2 = x % 2;
_data
| mv-apply element=l to typeof(long) on
let data = datatable (index: int, Arr: dynamic)
[
0, dynamic([1, 5, 3]),
1, dynamic([10, 2, 5, 7])
];
data
| mv-apply topElem=Arr to typeof(long) on
(
top 1 by element
top 1 by topElem
)
```

**Output**

| `xMod2` | l | element |
| index | Arr | topElem |
|--|--|--|
| 1 | [1, 3, 5, 7] | 7 |
| 0 | [2, 4, 6, 8] | 8 |
| 0 | [1, 5, 3] | 5 |
| 1 | [10, 2, 5, 7] | 10 |

### Calculating the sum of the largest two elements in an array
### Find top two elements in an array

The query outputs the sum of the top two even numbers (6 + 8 = 14) and the sum of the top two odd numbers (5 + 7 = 12).
The query saves the top two elements of an array in a new array column Top2.

:::moniker range="azure-data-explorer"
> [!div class="nextstepaction"]
> <a href="https://dataexplorer.azure.com/clusters/help/databases/Samples?query=H4sIAAAAAAAAA2WNsQ7CMBBD936FF6RkYGgmJJRPQAywV0FNq4pLLmqvKEH9eNqsePBw9j2TF3S9EwfbYNfs4uiRMcwc0EIYFyziE9oab1jWENw8fT3IBvf2HU2LqKzxKsg37g3s/n6CuTaV22wIn7NLiQro4ElJngdFHEcNjhWrqgsnmINDf1uPNdyHJydj95siXQv6B6sP8Fq9AAAA" target="_blank">Run the query</a>
> <a href="https://dataexplorer.azure.com/clusters/help/databases/Samples?query=H4sIAAAAAAAAA02NzQrCMBCE73mKOSYQwVZFUXrwHbyVIqmNEswf7SpW%2BvCmEcE9zMLMx4zVhE6RQpUfqdZqcOM7%2FdrDeJI49v0e3eiVMxfBaoZ0S%2FlzeL2RKCRWjZA5Kv6idYoSupPYNoI1BzZPsAnuuVAx2nHuLqskoAAaow5XboO%2FCQSP3MazUogo0X757EwYHs6p3rw1TiGWlVN3fbZmID4zIkPiA06i8CLdAAAA" target="_blank">Run the query</a>
::: moniker-end

```kusto
let _data =
range x from 1 to 8 step 1
| summarize l=make_list(x) by xMod2 = x % 2;
_data
| mv-apply l to typeof(long) on
let data = datatable (index: int, Arr: dynamic)
[
0, dynamic([5, 1, 3]),
1, dynamic([4, 10, 8, 7])
];
data
| mv-apply Arr2=Arr to typeof(long) on
(
top 2 by l
| summarize SumOfTop2=sum(l)
top 2 by Arr2
| summarize Top2=make_list(Arr2)
)
```

**Output**

| `xMod2` | l | SumOfTop2 |
| index | Arr | Top2 |
|--|--|--|
| 1 | [1,3,5,7] | 12 |
| 0 | [2,4,6,8] | 14 |
| 0 | [5, 1, 3] | [5, 3] |
| 1 | [4, 10, 8, 7] | [10, 8] |

### Select elements in arrays

Expand Down