Item	Description
List data type	The number of lists is not restricted. The size of single element cannot exceed 512 MB. We recommend that one lists contain no more than 8192 elements, and the maximum value length cannot exceed 1 MB.
Set data type	The number of sets is not restricted. The size of single element cannot exceed 512 MB. We recommend that one set contain no more than 8192 elements, and the maximum value length cannot exceed 1 MB.
SortedSet data type	The number of SortedSets is not restricted. The size of single element cannot exceed 512 MB. We recommend that one SortedSet contain no more than 8192 elements, and the maximum value length cannot exceed 1 MB.
Hash data type	The number of fields is not restricted. The size of single element cannot exceed 512 MB. We recommend that one field contain no more than 8192 elements, and the maximum value length cannot exceed 1 MB.
Restriction on the database number	Each instance supports 256 databases.
Redis commands supported	For more information, see Supported Redis commands.
Monitoring alert	ApsaraDB for Redis does not provide the capacity alert function. You can configure this function on CloudMonitor. For more information, see ApsaraDB for Redis monitoring. We recommend that you set alert for the following metrics: instance fault, instance master-slave switchover, connection usage, failed operation count, capacity usage, write bandwidth usage, and read bandwidth usage.
Expired data deletion policy	- Active expiration: The system periodically detects and deletes expired keys in the background. - Passive expiration: The system deletes expired keys when users access keys.
Idle connection recovery mechanism	Idle Refis connection is not automatically recovered by the server, and must be managed by the user.
Data persistence policy	AOF_FSYNC_EVERYSEC is enabled , and fysnc is performed every second.