why does the redis memory usage not reduce when del half of keys
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    The redis is used to save data but it costs a lot of memory, and its memory usage up to 52.5%.
    I del half of keys of the redis, and the return code of the del operation is ok, but its memory usage doesn't reduce.
    What's the reason? Thanks in Advance.

My operation code is as below:

    // save data
    m_pReply = (redisReply *)redisCommand(m_pCntxt, "set %b %b", mykey.data(), mykey.size(), &myval, sizeof(myval));
    // del data
    m_pReply = (redisReply *)redisCommand(m_pCntxt, "del %b", mykey.data(), mykey.size());

 