title: How to set TTL on Rocks DB properly?
body: <p>I am trying to use Rocks DB with TTL. The way I initialise rocks db is as below:
  <code>options.setCreateIfMissing(true).setWriteBufferSize(8 * SizeUnit.KB)
  .setMaxWriteBufferNumber(3)              .setCompressionType(CompressionType.LZ4_COMPRESSION).setKeepLogFileNum(1);
  db = TtlDB.open(options, this.dbpath, 10, false);</code></p>
  
  <p>I have set TTL to 10 seconds. But, the key value pairs are not being deleted after 10 seconds. Whats happening here?</p>