leveldb-api(3):DBcomparator.java

leveldb/DBComparator.java at master · dain/leveldb · GitHub

定义比较器：继承comparator接口

public interface DBComparator
        extends Comparator<byte[]>
{
    String name();

    /**
     * If {@code start < limit}, returns a short key in [start,limit).
     * Simple comparator implementations should return start unchanged,
     */
    byte[] findShortestSeparator(byte[] start, byte[] limit);

    /**
     * returns a 'short key' where the 'short key' is greater than or equal to key.
     * Simple comparator implementations should return key unchanged,
     */
    byte[] findShortSuccessor(byte[] key);
}

FindShortestSeparator(start, limit)作用是：如果start < limit，就返回一个key

FindShortSuccessor。直接对key中第一个以uint8方式+1的字节+1，清除该位后面的数据。