@Override
        public RSIndex create(byte dataType, ByteSlice buffer, int packCount) {
            assert dataType == ColumnType.STRING;
            return new RSIndex_CMap_V2(buffer, packCount);
        }
Seperate the index by value size.
We have 8 index chunk here.

0, 1, 2, 4, 8, 16, 32, 64
total posistion: 64 * 2

e.g. when comes a value with size 5, put it into "8" size chunk.
indexr-segment/src/main/java/io/indexr/segment/index/RSIndex_CMap_V2.java