What is ChunkReader.readChunk used for?
Cassandra uses the readChunk method which is in SimpleChunkReader and
CompressedChunkReader. This readChunk method is called from ChunkCache and
BufferManagingRebufferer (which is used when cache is not in use).
1. What exactly is the readChunk method used for? Is it to read into the
Key Cache (which maps partition keys to specific SSTable) or to actually
read rows from SSTables?
2. What is the position parameter in readChunk(long position, ByteBuffer