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learn-build-service-prod merged 4 commits into from
Nov 26, 2025
Merged

Repo sync for protected branch #2789

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b3f1aff
improvements
urishapira Nov 20, 2025
101e611
Merge pull request #7222 from urishapira/user/urishapira/hot-windows-…
Carolyn135 Nov 26, 2025
f5580d6
Merge pull request #7231 from MicrosoftDocs/main
learn-build-service-prod[bot] Nov 26, 2025
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Merging changes synced from https://github.com/MicrosoftDocs/dataexpl…
Nov 26, 2025
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15 changes: 8 additions & 7 deletions data-explorer/kusto/management/alter-merge-query-acceleration-policy-command.md
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Expand Up @@ -35,12 +35,13 @@ You must have at least [Database Admin](../access-control/role-based-access-cont

### JSON property bag

| Property | Type | Required | Description |
| ---------- | ---------- | ------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| IsEnabled | `Boolean` | | Indicates whether the policy is enabled. This property is required if no query acceleration policy is defined on the external table. |
| Hot | `Timespan` | | The hot period defined in the query acceleration policy. Minimum value = 1 d. This property is required if no query acceleration policy is defined on the external table. |
| HotWindows | `DateTime` | | One or more optional time windows. Delta data files created within these time windows are accelerated. |
| MaxAge | `Timespan` | | The external table returns accelerated data if the last index refresh time is greater than @now - MaxAge. Otherwise, external table operates in nonaccelerated mode. Default is 5 minutes. Minimum is 1 minute. |
| Property | Type | Required | Description |
| --------------------- | ---------- | ------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| IsEnabled | `Boolean` | | Indicates whether the policy is enabled. This property is required if no query acceleration policy is defined on the external table. |
| Hot | `Timespan` | | The hot period defined in the query acceleration policy. Minimum value = 1 d. This property is required if no query acceleration policy is defined on the external table. |
| HotWindows | `DateTime` | | One or more optional time windows. Delta data files created within these time windows are accelerated. |
| MaxAge | `Timespan` | | The external table returns accelerated data if the last index refresh time is greater than @now - MaxAge. Otherwise, external table operates in nonaccelerated mode. Default is 5 minutes. Minimum is 1 minute. |
| HotDateTimeColumn | `String` | | The name of a datetime column in the Delta table whose values will be used to determine hot-cache eligibility. When set, data files whose rows have values within the configured Hot period (and/or HotWindows) are selected for caching. |

> [!NOTE]
> Query acceleration is applied to data within a specific time period, defined as `timespan`, starting from the `modificationTime` as stated for each file in the [delta log](https://github.com/delta-io/delta/blob/master/PROTOCOL.md#add-file-and-remove-file).
Expand All @@ -50,7 +51,7 @@ You must have at least [Database Admin](../access-control/role-based-access-cont
In case the external table has query acceleration policy defined:

```json
{ "Hot": "1.00:00:00" }
{ "HotDateTimeColumn": "Col1" }
```

In case the external table doesn't have query acceleration policy defined:
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30 changes: 15 additions & 15 deletions data-explorer/kusto/management/alter-query-acceleration-policy-command.md
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Expand Up @@ -31,24 +31,24 @@ You must have at least [Database Admin](../access-control/role-based-access-cont

### JSON property bag
::: moniker range="microsoft-fabric"
| Property | Type | Required | Description |
| ---------- | ---------- | ------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| IsEnabled | `Boolean` | :heavy_check_mark: | Indicates whether the policy is enabled. |
| Hot | `Timespan` | :heavy_check_mark: | The hot period defined in the query acceleration policy. Minimum value = 1 d. |
| HotWindows | `DateTime` | | One or more optional time windows. Delta data files created within these time windows are accelerated. |
| MaxAge | `Timespan` | | The external table returns accelerated data if the last index refresh time is greater than @now - MaxAge. Otherwise, the external table operates in non-accelerated mode. Default is 5 minutes. Minimum is 1 minute. |
| HotDateTimeColumn | `String` | | Optional. The name of a datetime column in the Delta table whose values will be used to determine hot-cache eligibility. When set, data files whose rows have values within the configured Hot period (and/or HotWindows) are selected for caching. |
| Property | Type | Required | Description |
| ------------------- | ---------- | ------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| IsEnabled | `Boolean` | :heavy_check_mark: | Indicates whether the policy is enabled. |
| Hot | `Timespan` | :heavy_check_mark: | The hot period defined in the query acceleration policy. Minimum value = 1 d. |
| HotWindows | `DateTime` | | One or more optional time windows. Delta data files created within these time windows are accelerated. |
| MaxAge | `Timespan` | | The external table returns accelerated data if the last index refresh time is greater than @now - MaxAge. Otherwise, the external table operates in non-accelerated mode. Default is 5 minutes. Minimum is 1 minute. This property can also be overridden at query time by using the [`external_table()` function's](../query/external-table-function.md) `MaxAgeOverride` parameter. |
| HotDateTimeColumn | `String` | | Optional. The name of a datetime column in the Delta table whose values will be used to determine hot-cache eligibility. When set, data files whose rows have values within the configured Hot period (and/or HotWindows) are selected for caching. |
::: moniker-end

::: moniker range="azure-data-explorer"
| Property | Type | Required | Description |
| ---------- | ---------- | ------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| IsEnabled | `Boolean` | :heavy_check_mark: | Indicates whether the policy is enabled. |
| Hot | `Timespan` | :heavy_check_mark: | The hot period defined in the query acceleration policy. Minimum value = 1 d. |
| HotWindows | `DateTime` | | One or more optional time windows. Delta data files created within these time windows are accelerated. |
| MaxAge | `Timespan` | | The external table returns accelerated data if the last index refresh time is greater than @now - MaxAge. Otherwise, the external table operates in non-accelerated mode. Default is 5 minutes. Minimum is 1 minute. |
| ManagedIdentity | `string` | | Optional managed identity for which the query acceleration background operations are executed. This identity must have relevant delta table permissions and must be enabled for AutomatedFlows in the cluster / database managed identity policy. For more information, see [Managed identities overview](/azure/data-explorer/managed-identities-overview)|
| HotDateTimeColumn | `String` | | Optional. The name of a datetime column in the Delta table whose values will be used to determine hot-cache eligibility. When set, data files whose rows have values within the configured Hot period (and/or HotWindows) are selected for caching. |
| Property | Type | Required | Description |
| ------------------- | ---------- | ------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| IsEnabled | `Boolean` | :heavy_check_mark: | Indicates whether the policy is enabled. |
| Hot | `Timespan` | :heavy_check_mark: | The hot period defined in the query acceleration policy. Minimum value = 1 d. |
| HotWindows | `DateTime` | | One or more optional time windows. Delta data files created within these time windows are accelerated. |
| MaxAge | `Timespan` | | The external table returns accelerated data if the last index refresh time is greater than @now - MaxAge. Otherwise, the external table operates in non-accelerated mode. Default is 5 minutes. Minimum is 1 minute. This property can also be overridden at query time by using the [`external_table()` function's](../query/external-table-function.md) `MaxAgeOverride` parameter. |
| ManagedIdentity | `string` | | Optional managed identity for which the query acceleration background operations are executed. This identity must have relevant delta table permissions and must be enabled for AutomatedFlows in the cluster / database managed identity policy. For more information, see [Managed identities overview](/azure/data-explorer/managed-identities-overview). |
| HotDateTimeColumn | `String` | | Optional. The name of a datetime column in the Delta table whose values will be used to determine hot-cache eligibility. When set, data files whose rows have values within the configured Hot period (and/or HotWindows) are selected for caching. |
::: moniker-end
> [!NOTE]
> Query acceleration is applied to data within a specific time period, defined as `timespan`, starting from the `modificationTime` as stated for each file in the [delta log](https://github.com/delta-io/delta/blob/master/PROTOCOL.md#add-file-and-remove-file).
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2 changes: 1 addition & 1 deletion data-explorer/kusto/query/external-table-function.md
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Expand Up @@ -20,7 +20,7 @@ To accelerate queries over external delta tables, see [Query acceleration policy

## Syntax

`external_table(` *TableName* [`,` *MappingName* ] `)`
`external_table(` *TableName* [`,` *MappingName* / *MaxAgeOverride* ] `)`

[!INCLUDE [syntax-conventions-note](../includes/syntax-conventions-note.md)]

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