缓存策略命令cache policy command

本文介绍用于创建和更改缓存策略的命令This article describes commands used for creation and altering cache policy

显示缓存策略Displaying the cache policy

可以对数据库、表或具体化视图设置此策略，并可以使用以下命令之一来显示此策略：The policy can be set on a database, a table or a materialized view, and is displayed by using one of the following commands:

  • .show database DatabaseName policy caching.show database DatabaseName policy caching
  • .show table TableName policy caching.show table TableName policy caching
  • .show materialized-view MaterializedViewName policy caching.show materialized-view MaterializedViewName policy caching

更改缓存策略Altering the cache policy

.alter <entity_type> <database_or_table_or_materialized-view_name> policy caching hot = <timespan>

更改多个表的缓存策略（在相同数据库上下文中）：Altering cache policy for multiple tables (in the same database context):

.alter tables (table_name [, ...]) policy caching hot = <timespan>

缓存策略：Cache policy:

{
  "DataHotSpan": {
    "Value": "3.00:00:00"
  },
  "IndexHotSpan": {
    "Value": "3.00:00:00"
  }
}
  • entity_type：表、具体化视图、数据库或群集entity_type : table, materialized view, database, or cluster
  • database_or_table_or_materialized-view：如果实体为表或数据库，则应在命令中指定其名称，如下所示：database_or_table_or_materialized-view: if entity is table or database, its name should be specified in the command as follows -
    • database_name 或database_name or
    • database_name.table_name 或database_name.table_name or
    • table_name（在特定数据库的上下文中运行时）table_name (when running in the specific database's context)

删除缓存策略Deleting the cache policy

.delete <entity_type> <database_or_table_name> policy caching

示例Examples

显示数据库 MyDatabase 中表 MyTable 的缓存策略：Show cache policy for table MyTable in database MyDatabase:

.show table MyDatabase.MyTable policy caching

将表 MyTable 的缓存策略（在数据库上下文中）设置为 3 天：Setting cache policy of table MyTable (in database context) to 3 days:

.alter table MyTable policy caching hot = 3d
.alter materialized-view MyMaterializedView policy caching hot = 3d

将多个表的策略（在数据库上下文中）设置为 3 天：Setting policy for multiple tables (in database context), to 3 days:

.alter tables (MyTable1, MyTable2, MyTable3) policy caching hot = 3d

删除针对表设置的策略：Deleting a policy set on a table:

.delete table MyTable policy caching

删除针对具体化视图设置的策略：Deleting a policy set on a materialized view:

.delete materialized-view MyMaterializedView policy caching

删除针对数据库设置的策略：Deleting a policy set on a database:

.delete database MyDatabase policy caching