.alter materialized-view lookback

Applies to: ✅ Microsoft Fabric ✅ 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.

.alter materialized-view MaterializedViewName lookback LookbackPeriod

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.

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`	The time span that limits the period during which duplicates or updates are expected. For more information, see Lookback period.
LookbackColumn	`string`	A `string` column in the view which serves as the reference for the lookback period. If this column is empty, but the `lookback` has a value, then the materialized view uses a default lookback. For more information, see Lookback period.

The following examples show how to alter the lookback 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

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