LevelDB Table format

--- config: packet: bitsPerRow: 32 --- packet-beta 0-63: "sequence: fixed64" 64-95: "count: fixed32" 96-255: "data: record[count]"

--- config: packet: bitsPerRow: 32 --- packet-beta 0-7: "type: kTypeValue" 8-15: "key_len: varint32" 16-47: "key_data: uint8[key_len]" 48-55: "value_len: varint32" 56-87: "value_data: uint8[value_len]"

--- config: packet: bitsPerRow: 32 --- packet-beta 0-7: "type: kTypeDeletion" 8-15: "key_len: varint32" 16-47: "key_data: uint8[key_len]"

WriteBatch::rep_ :=
   sequence: fixed64
   count: fixed32
   data: record[count]
record :=
   kTypeValue varstring varstring         |
   kTypeDeletion varstring
varstring :=
   len: varint32
   data: uint8[len]

PUT and DELETE have different record structure.

We will use WriteBatch as the actuall format in our WAL.

sequence : 8 bytes, the index of sequence
count : 4 bytes, the count of operations
record : the record of PUT and DELETE opreation
- kTypeValue varstring(key) varstring(value) (for PUT)
- kTypeDeletion varstring(key) (for DELETION)
- Here, varint32 and uint8[len] make the varstring, which can be understanded as [key_len key_value] or [data_len data_value]

The Design of LevelDB's Table Format

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