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Limits

Last Updated: Dec 14, 2017
Items Limits
Data type ApsaraDB for Memcache supports only the key-value format data and does not support complex data types such as array, map, and list.
Data type Data of ApsaraDB for Memcache is stored in the memory, and it is not guaranteed that the cache data will not be lost. Therefore, ApsaraDB for Memcache is not suitable for storing data requiring high consistency.
Data size ApsaraDB for Memcache supports a maximum of 1 KB and 1 MB respectively for the key size and value size of a single piece of cached data. ApsaraDB for Memcache is not suitable for storing sizable data.
Transaction support ApsaraDB for Memcache does not support transactions. Therefore, ApsaraDB for Memcache is not suitable for storing data with transaction requirements. Data with transaction requirements must be written into the database directly.
Application scenarios When data accesses are evenly distributed, and there is no obvious hotspot or less popular data, a large number of access requests cannot hit the cache data in ApsaraDB for Memcache. Therefore, ApsaraDB for Memcache is ineffective when functioning as the database cache. You must give full consideration to the data access requirements of the business model when selecting the database cache.
Data deletion policy Expiration mechanism of ApsaraDB for Memcache is as follows: Each key expires at a user-defined time, and the key becomes inaccessible after expiration. The space occupied by the expired key is not recycled immediately after expiration, but is recycled at 02:00 every day.
Data expiration policy Similar to Memcached, Memcache uses the LRU algorithm to evict expired data, but it does not immediately remove the expired data from the recycle space. Operations of the recycle space are conducted regularly by a background program.
Connection ApsaraDB for Memcache server does not automatically disconnect idle client connections.
Data expiration We recommend to control and manage the expiration time of keys by the user.
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