Integer Types

The MySQL Protocol has a set of possible encodings for integers.

Protocol::FixedLengthInteger

Fixed-Length Integer Types

A fixed-length unsigned integer stores its value in a series of bytes with the least significant byte first.

The MySQL uses the following fixed-length unsigned integer variants:

• int<1>: 1 byte Protocol::FixedLengthInteger.
• int<2>: 2 byte Protocol::FixedLengthInteger. See int2store()
• int<3>: 3 byte Protocol::FixedLengthInteger. See int3store()
• int<4>: 4 byte Protocol::FixedLengthInteger. See int4store()
• int<6>: 6 byte Protocol::FixedLengthInteger. See int6store()
• int<8>: 8 byte Protocol::FixedLengthInteger. See int8store()

See int3store() for an example.

Protocol::LengthEncodedInteger

Length-Encoded Integer Type

An integer that consumes 1, 3, 4, or 9 bytes, depending on its numeric value

To convert a number value into a length-encoded integer:

Greater or equal	Lower than	Stored as
0	251	1-byte integer
251	216	0xFC + 2-byte integer
216	224	0xFD + 3-byte integer
224	264	0xFE + 8-byte integer

Similarly, to convert a length-encoded integer into its numeric value check the first byte.

Warning

If the first byte of a packet is a length-encoded integer and its byte value is 0xFE, you must check the length of the packet to verify that it has enough space for a 8-byte integer. If not, it may be an EOF_Packet instead.