In ApsaraDB for Memcache, the maximum length of a key is 250 bytes. The maximum length of a key-value pair is 4,194,291 bytes.

If the length of a key-value pair is greater than or equal to 4,194,292 bytes, an error message appears: object too large for cache.

If you use an object whose size is too large, more bandwidth is consumed and the queries per second (QPS) value drops. We recommend that the object be less than 10,000 bytes in length.