Memcached: update deletes all fields except the one updated

[rizlik]

The update routine in MemcachedClient replaces the full object with just the updated field

YCSB/memcached/src/main/java/site/ycsb/db/MemcachedClient.java

Line 211 in 12ce3a8

memcachedClient().replace(key, objectExpirationTime, toJson(values));

this script shows the issue.
memcached_test.sh.txt

This is a limit of storing the object as a big json blob and I don't see an easy solution.

One way to warn the users can be supporting update only when writeallfields is true.