The MySQL protocol is used between the MySQL Clients and the MySQL Server. It is implemented by

* the Connectors (Connector/C, ...)

* MySQL Proxy

* the MySQL Server itself for the slaves

The documentation is sparse and is split between:

http://forge.mysql.com/wiki/MySQL_Internals_ClientServer_Protocol

and the source files of the MySQL Server:

* sql/sql_parse.cc for the protocol basics

* dispatch_command()

* sql/sql_prepare.cc for the prepared statement protocol

* mysqld_stmt_prepare()

* mysqld_stmt_execute()

* mysqld_stmt_close()

* mysqld_stmt_reset()

* mysqld_stmt_fetch()

* mysql_stmt_get_longdata()

* sql/sql_repl.cc for the binlog protocol

* mysql_binlog_send()

* sql/protocol.cc for the value and type encoding

Tracking the MySQL Protocol

===========================

All the examples here are captured with::

$ ngrep -x -q -d lo0 '' 'port 3306'

A mysql client logs in

----------------------

Taking a look at the packet dump when a mysql-client logs in::

client -> server

<connect>

The client initiates the communication by connecting to the server.::

server -> client

36 00 00 00 0a 35 2e 35 2e 32 2d 6d 32 00 03 00 6....5.5.2-m2...

00 00 27 75 3e 6f 38 66 79 4e 00 ff f7 08 02 00 ..'u>o8fyN......

00 00 00 00 00 00 00 00 00 00 00 00 00 57 4d 5d .............WM]

6a 7c 53 68 32 5c 59 2e 73 00 j|Sh2\Y.s.

which responds with a handshake packet which contains the version, some flags and a password challenge.::

client -> server

3a 00 00 01 05 a6 03 00 00 00 00 01 08 00 00 00 :...............

00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................

00 00 00 00 72 6f 6f 74 00 14 cb b5 ea 68 eb 6b ....root.....h.k

3b 03 cb ae fb 9b df 5a cb 0f 6d b5 de fd ;......Z..m...

The client answers with username, some flags and the response to the challenge.::

server -> client

07 00 00 02 00 00 00 02 00 00 00 ...........

As the client provided the right password and the flags are fine, the server responds with a `OK packet`_. That closes auth-phase

and switches to the command-phase.::

client -> server

21 00 00 00 03 73 65 6c 65 63 74 20 40 40 76 65 !....select @@ve

72 73 69 6f 6e 5f 63 6f 6d 6d 65 6e 74 20 6c 69 rsion_comment li

6d 69 74 20 31 mit 1

The mysql client first checks the version string of the server and sends a `COM_QUERY`_ packet.::

server -> client

01 00 00 01 01 27 00 00 02 03 64 65 66 00 00 00 .....'....def...

11 40 40 76 65 72 73 69 6f 6e 5f 63 6f 6d 6d 65 .@@version_comme

6e 74 00 0c 08 00 1c 00 00 00 fd 00 00 1f 00 00 nt..............

05 00 00 03 fe 00 00 02 00 1d 00 00 04 1c 4d 79 ..............My

53 51 4c 20 43 6f 6d 6d 75 6e 69 74 79 20 53 65 SQL Community Se

72 76 65 72 20 28 47 50 4c 29 05 00 00 05 fe 00 rver (GPL)......

00 02 00 ...

The server responds with a resultset containing the version-string.::

client -> server

0e 00 00 00 03 73 65 6c 65 63 74 20 55 53 45 52 .....select USER

28 29 ()

For the prompt (\u ...) the mysql client also asks for the current username.::

server -> client

01 00 00 01 01 1c 00 00 02 03 64 65 66 00 00 00 ..........def...

06 55 53 45 52 28 29 00 0c 08 00 4d 00 00 00 fd .USER()....M....

01 00 1f 00 00 05 00 00 03 fe 00 00 02 00 0f 00 ................

00 04 0e 72 6f 6f 74 40 6c 6f 63 61 6c 68 6f 73 ...root@localhos

74 05 00 00 05 fe 00 00 02 00 t.........

which is 'root@localhost' in this example.

MySQL Packet header

-------------------

The packets that are exchanged between client and server look like::

...

T 127.0.0.1:51656 -> 127.0.0.1:3306 [AP]

01 00 00 00 01

The example shows a COM_QUIT packet. It starts (like all packets) with a 4 byte packet header:

* 3 byte length

* 1 byte sequence-id

The length is the length of the payload of the packet. If the payload is larger than 2^24-2 bytes the length is set to 2^24-1

and a additional packets are sent with the rest of the payload until the payload of a packet is less than 2^24-2 bytes.

The sequence-id is incremented with each packet for a sequence of packets. It is reset, when a new command begins.

Basic Types

===========

Integer

-------

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

* fixed length intergers

* length encoded integers

fixed length integer

....................

The fixed length integers can be of a byte-length 1, 2, 3, 4 or 8 and send their first byte first. The packet length

for example is::

01 00 00

is a 3-byte fixed length integer with the value `1`.

length encoded integer

......................

In other places integers have a variable size of 1, 3, 4 or 9 bytes depending on their value:

========================== ======

value bytes

========================== ======

``< 251`` 1

``>= 251 < (2^16 - 1)`` 3

``>= (2^16) < (2^24 - 1)`` 4

``>= (2^24)`` 9

========================== ======

The 1-byte values from 251 to 255 have a special meaning and aren't used for integers. Instead they

signal special packets or the 3 other variable length integer types:

======== === ===========

hex dec description

======== === ===========

``0xfb`` 251 NULL in the `Text Resultset Row`_

``0xfc`` 252 indicator for a 2-byte integer

``0xfd`` 253 indicator for a 3-byte integer

``0xfe`` 254 indicator for a 8-byte integer or first byte of a `EOF packet`_

``0xff`` 255 first byte of a `ERR packet`_

======== === ===========

They also send least significant byte first.

String

------

Strings appear in a few forms in the protocol:

_`Fixed Length String`

Fixed length strings have a known, hardcoded length. An example is the `sql-state` of the `ERR packet`_ which is always 5 byte long.

_`NUL-terminated String`

Strings that are terminated by a [00] byte.

_`Length Encoded String`

A length encoded string is a string that is prefixed with `length encoded integer`_ describing the length of the string.

_`End-of-packet String`

If a string is the last component of a packet, its length can be calculated from the overall-packet length minus the current position.

Describing packets

------------------

In this document we describe the packets by first defining their payload and provide examples with packet header and payload as

you would see it on the wire.::

<packetname>

<description>

direction: client -> server

payload:

<type> <description>

Example:

01 00 00 00 01

The `<type>` describes the sequence of bytes of the packet:

============== ===========

type description

============== ===========

1 1 byte `fixed length integer`_

2 2 byte `fixed length integer`_

3 3 byte `fixed length integer`_

4 4 byte `fixed length integer`_

8 8 byte `fixed length integer`_

lenenc-int `length encoded integer`_

string `NUL-terminated string`_

string[p] `End-of-packet string`_

string[`<n>`] fixed length string with the length `<n>`

lenenc-str `length encoded string`_

n a byte sequence of any length

============== ===========

.. attention::

Some packets have optional fields or a different layout depending on the `capability flags`_ that are sent as part of the

`Auth Response Packet`_.

If a field has a fixed value its description will show it as hex value in brackets like `[00]`.

Generic Response Packets

========================

For most of the commands the client sends to the server one of two packets is returned as response:

* `OK packet`_

* `ERR packet`_

OK packet

---------

::

OK

direction: server -> client

payload:

1 [00] the OK header

lenenc-int affected rows

lenenc-int last-insert-id

2 status flags

if capabilities & PROTOCOL_41:

2 warnings

example:

07 00 00 02 00 00 00 02 00 00 00 ...........

Status Flags

............

The status flags are a bit-field:

====== =============

flag constant name

====== =============

0x0001 SERVER_STATUS_IN_TRANS

0x0002 SERVER_STATUS_AUTOCOMMIT

0x0008 _`SERVER_MORE_RESULTS_EXISTS`

0x0010 SERVER_STATUS_NO_GOOD_INDEX_USED

0x0020 SERVER_STATUS_NO_INDEX_USED

0x0040 SERVER_STATUS_CURSOR_EXISTS

0x0080 SERVER_STATUS_LAST_ROW_SENT

0x0100 SERVER_STATUS_DB_DROPPED

0x0200 SERVER_STATUS_NO_BACKSLASH_ESCAPES

0x0400 SERVER_STATUS_METADATA_CHANGED

0x0800 SERVER_QUERY_WAS_SLOW

0x1000 SERVER_PS_OUT_PARAMS

====== =============

ERR packet

----------

::

ERR

direction: server -> client

payload:

1 [ff] the ERR header

2 error code

if capabilities & PROTOCOL_41:

1 '#' the sql-state marker

string[5] sql-state

all protocols:

string[p] error-message

example:

17 00 00 01 ff 48 04 23 48 59 30 30 30 4e 6f 20 .....H.#HY000No

74 61 62 6c 65 73 20 75 73 65 64 tables used

The Auth Phase

==============

A simple MySQL 4.1+ auth starts with:

1. the client connecting to the server

2. the server responds with the `Auth Challenge Packet`_

3. the client sends the `Auth Response Packet`_

4. the server responds with `OK Packet`_

If the auth fails, it sends a `ERR Packet`_ instead of a `OK Packet`_ and closes the connection:

1. the client connecting to the server

2. the server responds with the `Auth Challenge Packet`_

3. the client sends the `Auth Response Packet`_

4. the server responds with `ERR Packet`_ and closes connection

or the server denies the client right away if for example its IP is deny:

1. the client connecting to the server

2. the server responds with the `ERR Packet`_ and closes connection

MySQL 4.1+ server also may respond at step 4 with a `Old Password Auth Challenge Packet`_:

1. the client connecting to the server

2. the server responds with the `Auth Challenge Packet`_

3. the client sends the `Auth Response Packet`_

4. the server responds with the `Old Password Auth Challenge Packet`_

5. the client sends the `Old Password Auth Response Packet`_

6. the server responds with `OK Packet`_ or `ERR Packet`_ and closes the connection

Auth Challenge Packet

---------------------

As first packet the server sends a Auth Challenge to the client. It contains several other fields:

* the protocol version

* the mysql-server version string

* the server capabilities

* the auth challenge

The client answers with a `Auth Response Packet`_.

::

Auth Challenge Packet

response: Auth Response Packet

payload:

1 [0a] protocol version

string server version

4 connection id

string[8] challenge-part-1

1 [00] filler

2 capability flags

1 character set

2 status flags

string[13] reserved

if capabilities & SECURE_CONNECTION:

string[12] challenge-part-2

1 [00] filler

example:

36 00 00 00 0a 35 2e 35 2e 32 2d 6d 32 00 0b 00 6....5.5.2-m2...

00 00 64 76 48 40 49 2d 43 4a 00 ff f7 08 02 00 ..dvH@I-CJ......

00 00 00 00 00 00 00 00 00 00 00 00 00 2a 34 64 .............*4d

7c 63 5a 77 6b 34 5e 5d 3a 00 |cZwk4^]:.

`status flags` is defined as the `Status Flags`_ of the `OK packet`_.

Capability flags

................

The capability flags are used by the client and server to indicate which features

they support and want to use.

====== ============================== ==================================

flags constant name description

====== ============================== ==================================

0x0001 CLIENT_LONG_PASSWORD new more secure passwords

0x0002 CLIENT_FOUND_ROWS Found instead of affected rows

0x0004 CLIENT_LONG_FLAG Get all column flags

0x0008 CLIENT_CONNECT_WITH_DB One can specify db on connect

0x0010 CLIENT_NO_SCHEMA Don't allow database.table.column

0x0020 CLIENT_COMPRESS Can use compression protocol

0x0040 CLIENT_ODBC Odbc client

0x0080 _`CLIENT_LOCAL_FILES` Can use LOAD DATA LOCAL

0x0100 CLIENT_IGNORE_SPACE Ignore spaces before '('

0x0200 _`CLIENT_PROTOCOL_41` New 4.1 protocol

0x0400 CLIENT_INTERACTIVE This is an interactive client

0x0800 CLIENT_SSL Switch to SSL after handshake

0x1000 CLIENT_IGNORE_SIGPIPE IGNORE sigpipes

0x2000 CLIENT_TRANSACTIONS Client knows about transactions

0x4000 CLIENT_RESERVED Old flag for 4.1 protocol

0x8000 CLIENT_SECURE_CONNECTION New 4.1 authentication

====== ============================== ==================================

Auth Response Packet

--------------------

The client answers the `Auth Challenge Packet`_ with:

* its capability flags

* its password hashed with challenge

If the capabilities have a `CLIENT_PROTOCOL_41`_ flag set the response packet is::

Auth Response Packet 4.1+

payload:

4 capability flags

4 max-packet size

1 character set

string[23] reserved

string username

if capabilities & SECURE_CONNECTION:

lenenc-str auth-response

else:

string auth-response

all:

string[p] database

If not, it is::

Auth Response Packet pre-4.1

payload:

2 capability flags

3 max-packet size

string username

string auth-response

`capability flags` are the same as defined in the `Capability flags`_ of the `Auth Challenge Packet`_ plus:

========== ============================== ==================================

flags constant name description

========== ============================== ==================================

0x00010000 _`CLIENT_MULTI_STATEMENTS` Enable/disable multi-stmt support

0x00020000 _`CLIENT_MULTI_RESULTS` Enable/disable multi-results

0x00040000 _`CLIENT_PS_MULTI_RESULTS` Multi-results in PS-protocol

0x40000000 CLIENT_SSL_VERIFY_SERVER_CERT

0x80000000 CLIENT_REMEMBER_OPTIONS

========== ============================== ==================================

Old Password Auth Challenge Packet

----------------------------------

In case the server stored a password in the OLD_PASSWORD() fashion for this

user the client has to use another hash for the password.

::

Old Password Auth Challenge Packet

ask the client to send the password hashed with insecure hash-function

payload:

1 [fe]

example:

01 00 00 02 fe

Old Password Auth Response Packet

---------------------------------

::

Old Password Auth Response Packet

the password hashed with old, insecure hash-function

payload:

string auth-response

example:

09 00 00 03 5c 49 4d 5e 4e 58 4f 47 00 ....\IM^NXOG.

The Command Phase

=================

In the command phase the client sends a command packet with the sequence-id [00]::

13 00 00 00 03 53 ...

01 00 00 00 01

^^- command-byte

^^---- sequence-id == 0

The first byte of the payload describes the command-type like:

=== ======================

hex constant name

=== ======================

00 `COM_SLEEP`_

01 `COM_QUIT`_

02 `COM_INIT_DB`_

03 `COM_QUERY`_

04 `COM_FIELD_LIST`_

05 `COM_CREATE_DB`_

06 `COM_DROP_DB`_

07 `COM_REFRESH`_

08 `COM_SHUTDOWN`_

09 `COM_STATISTICS`_

0a `COM_PROCESS_INFO`_

0b `COM_CONNECT`_

0c `COM_PROCESS_KILL`_

0d `COM_DEBUG`_

0e `COM_PING`_

0f `COM_TIME`_

10 `COM_DELAYED_INSERT`_

11 `COM_CHANGE_USER`_

12 COM_BINLOG_DUMP

13 `COM_TABLE_DUMP`_

14 `COM_CONNECT_OUT`_

15 COM_REGISTER_SLAVE

16 `COM_STMT_PREPARE`_

17 `COM_STMT_EXECUTE`_

18 `COM_STMT_SEND_LONG_DATA`_

19 `COM_STMT_CLOSE`_

1a `COM_STMT_RESET`_

1b `COM_SET_OPTION`_

1c `COM_STMT_FETCH`_

1d `COM_DAEMON`_

=== ======================

.. _COM_SLEEP: `unhandled commands`_

.. _COM_CONNECT: `unhandled commands`_

.. _COM_TIME: `unhandled commands`_

.. _COM_DELAYED_INSERT: `unhandled commands`_

.. _COM_CONNECT_OUT: `unhandled commands`_

.. _COM_TABLE_DUMP: `unhandled commands`_

.. _COM_DAEMON: `unhandled commands`_

The commands belong to

* the `Old Commands`_

* the `Prepared Statements`_ Commands

* the `Stored Procedures`_ Commands

* or the Replication Commands

Old Commands

============

The old commands are supported for all MySQL Server versions from 3.23 upwards (and perhaps older).

unhandled commands

------------------

* COM_SLEEP

* COM_CONNECT

* COM_TIME

* COM_DELAYED_INSERT

* COM_DAEMON

These commands are only used internally by the server or are deprecated. Sending the to the server always results in a

`ERR packet`_.

COM_QUIT

--------

::

COM_QUIT

tells the server that the client wants to close the connection

direction: client -> server

response: either a connection close or a OK packet

payload:

1 [01] COM_QUIT

Example:

01 00 00 00 01

COM_INIT_DB

-----------

::

COM_INIT_DB

change the default schema of the connection

direction: client -> server

response: OK or ERR

payload:

1 [02] COM_INIT_DB

string[p] schema name

example:

05 00 00 00 02 74 65 73 74 .....test

COM_QUERY

---------

A COM_QUERY is used to send the server a text-based query that is executed immediately.

The server replies to a COM_QUERY packet with a `COM_QUERY Response`_.

::

COM_QUERY

tells the server to execute a text-based query

direction: client -> server

payload:

1 [03] COM_QUERY

string[p] the query the server shall execute

Example:

21 00 00 00 03 73 65 6c 65 63 74 20 40 40 76 65 !....select @@ve

72 73 69 6f 6e 5f 63 6f 6d 6d 65 6e 74 20 6c 69 rsion_comment li

6d 69 74 20 31 mit 1

The length of the query-string is a taken from the packet length - 1.

API call: `mysql_query() <http://dev.mysql.com/doc/refman/5.1/en/mysql-query.html>`_

COM_QUERY Response

..................

The query-response packet is a meta packet which can be one of

* a `ERR packet`_

* a `OK packet`_

* a `LOCAL INFILE request`_

* a `Text Resultset`_

The type of the packet is defined by the type-identifier::

COM_QUERY response

response to a COM_QUERY packet

payload

lenenc-int number of columns in the resultset

If the number of columns in the resultset is 0, this is a `OK packet`_.

If it is not a valid `length encoded integer`_ it is a either a `ERR packet`_ or a `LOCAL INFILE request`_.

Text Resultset

**************

A Text Resultset is a possible `COM_QUERY Response`_.

It is made up of a two parts:

* the column definition

* the rows

which consists of a sequence of packets.

The column defintion is starts with a packet containing the column-count and is

followed by as many `Column Definition`_ packets as we have columns and is terminated

by a `EOF packet`.

Each row is a packet too. The rows are terminated by another `EOF packet`_. In case

the query could generate the column-definition, but generating the rows afterwards

failed a `ERR packet`_ may be sent instead of the last `EOF packet`_.

* a packet containing a `length encoded integer`_ column-count

* column-count * `Column Definition`_ packets

* `EOF packet`_

* row-count * packets as in `Text Resultset Row`_ format

* `EOF packet`_

In the example we use `|` to show the packet borders::

01 00 00 01 01|27 00 00 02 03 64 65 66 00 00 00 .....'....def...

11 40 40 76 65 72 73 69 6f 6e 5f 63 6f 6d 6d 65 .@@version_comme

6e 74 00 0c 08 00 1c 00 00 00 fd 00 00 1f 00 00| nt..............

05 00 00 03 fe 00 00 02 00|1d 00 00 04 1c 4d 79 ..............My

53 51 4c 20 43 6f 6d 6d 75 6e 69 74 79 20 53 65 SQL Community Se

72 76 65 72 20 28 47 50 4c 29|05 00 00 05 fe 00 rver (GPL)......

00 02 00 ...

It has one column (`01 00 00 01 01`) and a field named `@@version_comment` whichs is a `MYSQL_TYPE_VAR_STRING`_ [fd].

It has one row and its one value is `MySQL Community Server (GPL)`.

If the `SERVER_MORE_RESULTS_EXISTS`_ flag is set in the last `EOF packet`_ a `multi-resultset`_ is sent.

It may also be resultset with an closing `ERR packet`_:

* a packet containing a `length encoded integer`_ column-count

* column-count * `Column Definition`_ packets

* `EOF packet`_

* `ERR packet`_

which is generated for queries like `EXPLAIN SELECT * FROM dual`.

Column Types

,,,,,,,,,,,,

=== ======================

hex constant name

=== ======================

00 _`MYSQL_TYPE_DECIMAL`

01 _`MYSQL_TYPE_TINY`

02 _`MYSQL_TYPE_SHORT`

03 _`MYSQL_TYPE_LONG`

04 _`MYSQL_TYPE_FLOAT`

05 _`MYSQL_TYPE_DOUBLE`

06 _`MYSQL_TYPE_NULL`

07 _`MYSQL_TYPE_TIMESTAMP`

08 _`MYSQL_TYPE_LONGLONG`

09 _`MYSQL_TYPE_INT24`

0a _`MYSQL_TYPE_DATE`

0b _`MYSQL_TYPE_TIME`

0c _`MYSQL_TYPE_DATETIME`

0d _`MYSQL_TYPE_YEAR`

0e _`MYSQL_TYPE_NEWDATE`

0f _`MYSQL_TYPE_VARCHAR`

10 _`MYSQL_TYPE_BIT`

f6 _`MYSQL_TYPE_NEWDECIMAL`

f7 _`MYSQL_TYPE_ENUM`

f8 _`MYSQL_TYPE_SET`

f9 _`MYSQL_TYPE_TINY_BLOB`

fa _`MYSQL_TYPE_MEDIUM_BLOB`

fb _`MYSQL_TYPE_LONG_BLOB`

fc _`MYSQL_TYPE_BLOB`

fd _`MYSQL_TYPE_VAR_STRING`

fe _`MYSQL_TYPE_STRING`

ff _`MYSQL_TYPE_GEOMETRY`

=== ======================

Column Definition

,,,,,,,,,,,,,,,,,

If the PROTOCOL_41 capability is set::

Column Definition - 4.1+

payload:

lenenc-str catalog

lenenc-str schema

lenenc-str table

lenenc-str org_table

lenenc-str name

lenenc-str org_name

1 filler [00]

2 character set

4 column length

1 type

2 flags

1 decimals

2 filler [00] [00]

If not ::

Column Definition - pre-4.1

payload:

lenenc-str table

lenenc-str name

1 [03]

3 column length

1 [01]

1 type

1 [02] or [03]

if above field == 02:

1 flags

if ... == 03:

2 flags

all:

1 decimals

Text Resultset Row

,,,,,,,,,,,,,,,,,,

A row with the data for each column.

* Integers are sent as `length encoded integer`_.

* everything else sent as `length encoded string`_.

If a field is NULL `0xfb` is sent as described in `length encoded integer`_.

EOF packet

,,,,,,,,,,

::

EOF

direction: server -> client

payload:

1 [fe] the EOF header

if capabilities & PROTOCOL_41:

2 warning count

2 status flags

example:

05 00 00 05 fe 00 00 02 00

The status flags are a bit-field as defined in the `Status Flags`_ of the `OK packet`_.

LOCAL INFILE request

********************

If the client wants to LOAD DATA from a LOCAL file into the server it sends::

LOAD DATA LOCAL INFILE '<filename>' INTO TABLE <table>;

The LOCAL keyword triggers the server to send a LOAD INFILE packet asks the client

to send the file via a `LOCAL INFILE data`_ response.

The client has to set the `CLIENT_LOCAL_FILES`_ capability.

::

LOCAL INFILE packet

direction: server -> client

response: LOCAL INFILE data

payload:

1 [fb] LOCAL INFILE

string[p] filename the client shall send

example:

0c 00 00 01 fb 2f 65 74 63 2f 70 61 73 73 77 64 ...../etc/passwd

LOCAL INFILE data

,,,,,,,,,,,,,,,,,

The client sends its file data AS IS to the server in response to a `LOCAL INFILE request`_.

::

LOAD INFILE data

direction: client data

payload:

n the filedata

COM_FIELD_LIST

--------------

::

COM_FIELD_LIST

get the column definition of a tables

direction: client -> server

response:

payload:

1 [04] COM_FIELD_LIST

string table

string[p] field wildcard

API call: `mysql_list_fields() <http://dev.mysql.com/doc/refman/5.1/en/mysql-list-fields.html>`_

COM_FIELD_LIST response

.......................

The response to a `COM_FIELD_LIST`_ can either be a

* a `ERR packet`_ or the

* first half of a `Text Resultset`_

* a packet containing a `length encoded integer`_ column-count

* column-count * `Column Definition`_ packets

* `EOF packet`_

COM_CREATE_DB

-------------

::

COM_CREATE_DB

create a schema

direction: client -> server

response: OK or ERR

payload:

1 [05] COM_CREATE_DB

string[p] schema name

example:

05 00 00 00 05 74 65 73 74 .....test

COM_DROP_DB

-----------

::

COM_DROP_DB

drop a schema

direction: client -> server

response: OK or ERR

payload:

1 [06] COM_DROP_DB

string[p] schema name

example:

05 00 00 00 06 74 65 73 74 .....test

COM_REFRESH

-----------

a low-level version of several `FLUSH ...` and `RESET ...` commands.

==== =============== ===========

flag constant name description

==== =============== ===========

0x01 REFRESH_GRANT Refresh grant tables `FLUSH PRIVILEGES`

0x02 REFRESH_LOG Start on new log file `FLUSH LOGS`

0x04 REFRESH_TABLES close all tables `FLUSH TABLES`

0x08 REFRESH_HOSTS Flush host cache `FLUSH HOSTS`

0x10 REFRESH_STATUS Flush status variables `FLUSH STATUS`

0x20 REFRESH_THREADS Flush thread cache

0x40 REFRESH_SLAVE Reset master info and restart slave thread `RESET SLAVE`

0x80 REFRESH_MASTER Remove all bin logs in the index and truncate the index `RESET MASTER`

==== =============== ===========

::

COM_REFRESH

get a list of active threads

direction: client -> server

response: OK or ERR

payload:

1 [07] COM_REFRESH

1 flags

COM_SHUTDOWN

------------

COM_SHUTDOWN is used to shutdown the mysql-server.

Even if several shutdown types are define, right now only one is use: SHUTDOWN_WAIT_ALL_BUFFERS

==== ============================== ===========

type constant name description

==== ============================== ===========

0x00 SHUTDOWN_DEFAULT defaults to SHUTDOWN_WAIT_ALL_BUFFERS

0x01 SHUTDOWN_WAIT_CONNECTIONS wait for existing connections to finish

0x02 SHUTDOWN_WAIT_TRANSACTIONS wait for existing trans to finish

0x08 SHUTDOWN_WAIT_UPDATES wait for existing updates to finish (=> no partial MyISAM update)

0x10 SHUTDOWN_WAIT_ALL_BUFFERS flush InnoDB buffers and other storage engines' buffers

0x11 SHUTDOWN_WAIT_CRITICAL_BUFFERS don't flush InnoDB buffers, flush other storage engines' buffers

0xfe KILL_QUERY

0xff KILL_CONNECTION

==== ============================== ===========

`SHUTDOWN` privilege is required.

::

COM_SHUTDOWN

get a list of active threads

direction: client -> server

response: EOF or ERR

payload:

1 [08] COM_SHUTDOWN

if shutdown type != 0x00:

1 shutdown type

Clients before 4.1.3 don't send the `shutdown type`. `0x00` is assumed in that case.

COM_STATISTICS

--------------

Get a human readable string of internal statistics.

::

COM_STATISTICS

get a list of active threads

direction: client -> server

response: string[p]

payload:

1 [09] COM_STATISTICS

COM_PROCESS_INFO

----------------

The COM_PROCESS_INFO command is deprecated. `SHOW PROCESSLIST` should be used instead.

It either returns a: