Logical packets MySQL

The topic is: the contents of logical packets in MySQL version 5.0 client/server communication.

The description is of logical packets. There will be only passing mention of non-logical considerations, such as physical packets, transport, buffering, and compression. If you are interested in those topics, you may wish to consult another document: "MySQL Client - Server Protocol Documentation" in the file net_doc.txt in the internals directory of the mysqldoc MySQL documentation repository.

The description is of the version-5.0 protocol at the time of writing. Most of the examples show version- 4.1 tests, which is okay because the changes from version-4.1 to version-5.0 were small.

A typical description of a packet will include:

"Bytes and Names". This is intended as a quick summary of the lengths and identifiers for every field in the packet, in order of appearance. The "Bytes" column contains the length in bytes. The Names column contains names which are taken from the MySQL source code whenever possible. If the version-4.0 and version-4.1 formats differ significantly, we will show both formats.

Descriptions for each field. This contains text notes about the usage and possible contents.

(If necessary) notes about alternative terms. Naming in this document is not authoritative and you will often see different words used for the same things, in other documents.

(If necessary) references to program or header files in the MySQL source code. An example of such a reference is: sql/protocol.cc net_store_length() which means "in the sql subdirectory, in the protocol.cc file, the function named net_store_length".

An Example. All examples have three columns:

-- the field name
-- a hexadecimal dump
-- an ascii dump, if the field has character data

All spaces and carriage returns in the hexadecimal dump are there for formatting purposes only.

In the later sections, related to prepared statements, the notes should be considered unreliable and there are no examples.


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