Chunk v4 format
// Header
+-----------------------------------+
| Magic Number (uint32, 4 bytes) |
+-----------------------------------+
| Version (1 byte) |
+-----------------------------------+
| Encoding (1 byte) |
+-----------------------------------+
// Blocks
+--------------------+----------------------------+
| block 1 (n bytes) | checksum (uint32, 4 bytes) |
+--------------------+----------------------------+
| block 1 (n bytes) | checksum (uint32, 4 bytes) |
+--------------------+----------------------------+
| ... |
+--------------------+----------------------------+
| block N (n bytes) | checksum (uint32, 4 bytes) |
+--------------------+----------------------------+
// Metas
+------------------------------------------------------------------------------------------------------------------------+
| #blocks (uvarint) |
+--------------------+-----------------+-----------------+------------------+---------------+----------------------------+
| #entries (uvarint) | minTs (uvarint) | maxTs (uvarint) | offset (uvarint) | len (uvarint) | uncompressedSize (uvarint) |
+--------------------+-----------------+-----------------+------------------+---------------+----------------------------+
| #entries (uvarint) | minTs (uvarint) | maxTs (uvarint) | offset (uvarint) | len (uvarint) | uncompressedSize (uvarint) |
+--------------------+-----------------+-----------------+------------------+---------------+----------------------------+
| ... |
+--------------------+-----------------+-----------------+------------------+---------------+----------------------------+
| #entries (uvarint) | minTs (uvarint) | maxTs (uvarint) | offset (uvarint) | len (uvarint) | uncompressedSize (uvarint) |
+--------------------+-----------------+-----------------+------------------+---------------+----------------------------+
| checksum (uint32, 4 bytes) |
+------------------------------------------------------------------------------------------------------------------------+
// Structured Metadata
+---------------------------------+
| #labels (uvarint) |
+---------------+-----------------+
| len (uvarint) | value (n bytes) |
+---------------+-----------------+
| ... |
+---------------+-----------------+
| checksum (uint32, 4 bytes) |
+---------------------------------+
// Footer
+-----------------------+--------------------------+
| len (uint64, 8 bytes) | offset (uint64, 8 bytes) | // offset to Structured Metadata
+-----------------------+--------------------------+
| len (uint64, 8 bytes) | offset (uint64, 8 bytes) | // offset to Metas
+-----------------------+--------------------------+