.alter materialized-view lookback

  • Article
  • 03/19/2025

Applies to: ✅ Azure Data Explorer

Alters the lookback value of an existing materialized view. For more information on the lookback property, see materialized view create command properties.

Permissions

You must have at least Materialized View Admin permissions to run this command.

Syntax

.alter materialized-view MaterializedViewName lookback LookbackPeriod

Learn more about syntax conventions.

Parameters

Name Type Required Description
MaterializedViewName string ✔️ The name of the materialized view.
LookbackPeriod timespan ✔️ The time span that limits the period during which duplicates or updates are expected.

Returns

Output schema:

Name Type Description
Name string Name of the materialized view.
SourceTable string Name of source table on which the view is defined.
Query string Query definition of the materialized view.
MaterializedTo datetime Maximum materialized ingestion_time() timestamp in source table. For more information, see how materialized views work.
LastRun datetime Last time materialization was run.
LastRunResult string Result of last run. Returns Completed for successful runs, otherwise Failed.
IsHealthy bool true when view is considered healthy, false otherwise. View is considered healthy if it was successfully materialized up to the last hour (MaterializedTo is greater than ago(1h)).
IsEnabled bool true when view is enabled (see Disable or enable materialized view).
Folder string Folder under which the materialized view is created.
DocString string Description assigned to the materialized view.
AutoUpdateSchema bool Whether the view is enabled for auto updates.
EffectiveDateTime datetime Effective date time of the view, determined during creation time (see .create materialized-view).
Lookback timespan Time span limiting the period of time in which duplicates are expected.

Examples

The following examples show how to alter the lookback of a materialized view.

Set the lookback property of a materialized view

The following example sets the lookback period of the materialized view, MyView, to six hours.

.alter materialized-view MyView lookback 6h

Output

Name SourceTable Query MaterializedTo LastRun LastRunResult IsHealthy IsEnabled Folder DocString AutoUpdateSchema EffectiveDateTime Lookback
MyView MyTable MyTable | summarize take_any(*) by Column1 2023-02-26T16:40:03.3345704Z 2023-02-26T16:44:15.9033667Z Completed true true true 2023-02-23T14:01:42.5172342Z 6:00:00:00

Remove the lookback of a materialized view

The following example removes the lookback period of the materialized view, MyView.

.alter materialized-view MyView lookback timespan(null)

Output

Name SourceTable Query MaterializedTo LastRun LastRunResult IsHealthy IsEnabled Folder DocString AutoUpdateSchema EffectiveDateTime Lookback
MyView MyTable MyTable | summarize take_any(*) by Column1 2023-02-26T16:40:03.3345704Z 2023-02-26T16:44:15.9033667Z Completed true true true 2023-02-23T14:01:42.5172342Z

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