.alter table policy caching command

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Applies to: ✅ Azure Data Explorer

Change's the table's cache policy. To speed up queries, data is cached on processing nodes, in SSD, or even in RAM. The cache policy allows your database to describe the data artifacts that it uses, so that more important data can take priority.

Permissions

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

Syntax

.alter table [DatabaseName .]TableName policy caching PolicyParameters

Learn more about syntax conventions.

Parameters

Name Type Required Description
DatabaseName string The name of the database. When you run the command from the database context that contains the table to alter, DatabaseName is not required.
TableName string ✔️ The name of the table. Use without DatabaseName when running in the required database's context.
PolicyParameters string ✔️ The policy parameters to set. See cache policy.

Examples

Set cache policy of a table

Set the caching policy to include the last 30 days.

.alter table MyTable policy caching hot = 30d

Set the cache policy of table with extra hot-cache windows

Set the caching policy to include the last 30 days and extra data from January and April 2021.

.alter table MyTable policy caching 
        hot = 30d,
        hot_window = datetime(2021-01-01) .. datetime(2021-02-01),
        hot_window = datetime(2021-04-01) .. datetime(2021-05-01)

Set the caching policy for multiple tables

Set the caching policy for several tables to include the last 30 days, and data from January and April 2021.

.alter tables (MyTable1, MyTable2, MyTable3) policy caching 
        hot = 30d,
        hot_window = datetime(2021-01-01) .. datetime(2021-02-01),
        hot_window = datetime(2021-04-01) .. datetime(2021-05-01)

Set the caching policy for multiple tables with extra hot-cache windows

Set the caching policy for several tables to include the last 30 days.

.alter tables (MyTable1, MyTable2, MyTable3) policy caching hot = 30d