keyspec.txt

Key spec.

The following grammar specifies the keys used for storing each DAG and
related keys in a B-tree.

Basic Types

The following basic types are used as terminals in the rest of the grammar. Each
type must be serialized in little-endian format.

""      empty string
byte    1 byte (8-bits)


Non-terminals

The following specifies the rest of the key grammar. Note that quoted strings
represent terminals, and should be interpreted with C semantics (e.g. "\x01"
represents the byte 0000 0001). Also note that we use the * operator as
shorthand for repetition (e.g. ("\x01"*2) is "\x01\x01"). When used as a unary
operator, * means that the repetition can occur 0 or more times.

key     ::=  name subkey ""         any key is a name followed by a subkey
name    ::=  sstring                name of the key space
subkey  ::=
          |  "\x01" id ival         dskey, data store key
          |  "\x02" ival            ikey, i index key
          |  "\x03" id version      headkey, head index key
          |  "\x04" version         vkey, version index key
          |  "\x05" sstring         uskey, user store key
ival    ::=  lbeint                 i value, monotonically increasing number
id      ::=  string                 used to identify data store values
version ::=  lbeint                 version number
lbeint  ::=  byte (byte*)           Large int - byte is the number of bytes in
                                    (byte*) (max 254). (byte*) should be
                                    interpreted as an unsigned integer in big
                                    endian format.
sstring ::=  byte (byte*) "\x00"    Size string - byte is the number of bytes in
                                    (byte*) (max 254). (byte*) is zero or more
                                    ASCII encoded characters excluding '\x00'.
                                    The string is ended with a trailing '\x00'
                                    byte.
string  ::=  (byte*) "\x00"         String - (byte*) is zero or more ASCII
                                    encoded characters excluding '\x00'. The
                                    string is ended with a trailing '\x00' byte.
opts    ::=  byte                   option bits, single byte:
                                      0x01 = conflict, when a merge with this
                                      item failed
                                      0x02 = delete, if the head is deleted


The values for the given keys are as follows:
key: "\x01", value: BSON serialized javascript object
key: "\x02", value: key of subtype "\x03"
key: "\x03", value: opts ival
key: "\x04", value: key of subtype "\x01"
key: "\x05", value: (byte*) one or more bytes (node Buffer)




Copied from http://bsonspec.org/spec.html and modified by Tim Kuijsten