QUERY_EVENT

The QUERY_EVENT records text-based SQL statements for statement-based replication, capturing the query string and execution context like the default database.

This event is written into the binary log file for:

• Statement-based replication (updating statements).

• DDLs.

• COMMIT related to nontransactional engines (like MyISAM or BLACKHOLE).

Header

• Event Type = 0x02.

Fields

Fixed data part:

• uint<4> The ID of the thread that issued this statement on the master.

• uint<4> The time in seconds that the statement took to execute.

• uint<1> The length of the name of the database which was the default database when the statement was executed. This name appears later, in the variable data part. It is necessary for statements such as INSERT INTO t VALUES(1) that don't specify the database and rely on the default database previously selected by USE.

• uint<2> The error code resulting from execution of the statement on the master.

• uint<2> The length of the status variable block.

Variable data part:

• byte Zero or more status variables. Each status variable consists of one byte code identifying the variable stored, followed by the value of the variable. The format of the value is variable-specific. The number of bytes 'n' is the length of the status variable block (read in fixed data part).

• string The default database name (null-terminated).

• string The SQL statement. By subtraction the size of the statement can be known.

Status variables

Q_FLAGS2_CODE (0x00)

• uint<4> bitmask.

Value	Option
0x00004000	OPTION_AUTO_IS_NULL
0x00080000	OPTION_NOT_AUTOCOMMIT
0x04000000	OPTION_NO_FOREIGN_KEY_CHECKS
0x08000000	OPTION_RELAXED_UNIQUE_CHECKS

Q_SQL_MODE_CODE (0x01)

• uint<8> 8-byte bitmask.

Value	Option
0x00000001	MODE_REAL_AS_FLOAT
0x00000002	MODE_PIPES_AS_CONCAT
0x00000004	MODE_ANSI_QUOTES
0x00000008	MODE_IGNORE_SPACE
0x00000010	MODE_NOT_USED
0x00000020	MODE_ONLY_FULL_GROUP_BY
0x00000040	MODE_NO_UNSIGNED_SUBTRACTION
0x00000080	MODE_NO_DIR_IN_CREATE
0x00000100	MODE_POSTGRESQL
0x00000200	MODE_ORACLE
0x00000400	MODE_MSSQL
0x00000800	MODE_DB2
0x00001000	MODE_MAXDB
0x00002000	MODE_NO_KEY_OPTIONS
0x00004000	MODE_NO_TABLE_OPTIONS
0x00008000	MODE_NO_FIELD_OPTIONS
0x00010000	MODE_MYSQL323
0x00020000	MODE_MYSQL40
0x00040000	MODE_ANSI
0x00080000	MODE_NO_AUTO_VALUE_ON_ZERO
0x00100000	MODE_NO_BACKSLASH_ESCAPES
0x00200000	MODE_STRICT_TRANS_TABLES
0x00400000	MODE_STRICT_ALL_TABLES
0x00800000	MODE_NO_ZERO_IN_DATE
0x01000000	MODE_NO_ZERO_DATE
0x02000000	MODE_INVALID_DATES
0x04000000	MODE_ERROR_FOR_DIVISION_BY_ZERO
0x08000000	MODE_TRADITIONAL
0x10000000	MODE_NO_AUTO_CREATE_USER
0x20000000	MODE_HIGH_NOT_PRECEDENCE
0x40000000	MODE_NO_ENGINE_SUBSTITUTION
0x80000000	MODE_PAD_CHAR_TO_FULL_LENGTH

Q_CATALOG_NZ_CODE (0x02)

• uint<1> length

• string<length +1> catalog name + '\0'

Q_AUTO_INCREMENT (0x03)

• uint<2> auto_increment increment

• uint<2> auto_increment offset

Q_CHARSET_CODE (0x04)

• uint<2> client character set

• uint<2> collation_connection

• uint<2> collation_server

Q_TIMEZONE_CODE (0x05)

• uint<1> length

• string time zone

Q_CATALOG_NZ_CODE (0x06)

• uint<1> length

• string catalog

Q_LC_TIME_NAMES_CODE (0x07)

• uint<2> code The mapping between code and names are defined in sql_locale.cc.

Q_CHARSET_DATABASE_CODE (0x08)

• uint<2> database collation

Q_TABLE_MAP_FOR_UPDATE_CODE (0x09)

• uint<8> table bittmask Every bit of this variable represents a table, and is set to 1 if the corresponding table is to be updated by this statement.

Q_MASTER_DATA_WRITTEN_CODE (0x0A)

• Not in use any more

• uint<4> original event length

Q_INVOKER (0x0B|)

• uint<1> user name length

• string user name

• uint<1> host name length

• string host name

Q_UPDATED_DB_NAMES (0x0C)

• MySQL only

• uint<1> count

• for (i=0;i < count; i++)

  • string Null terminated database name

Q_MICROSECONDS (0x0D)

• MySQL only

• uint<3> microsecond part

Q_HRNOW (0x80)

• MariaDB only

• uint<3> microsecond part

Q_XID (0x81)

• MariaDB only

• uint<8> xid

Example With CRC32

71 17 28 5a 02 8c 27 00  00 55 00 00 00 01 09 00  q.(Z..'..U......
00 00 00 66 01 00 00 00  00 00 00 00 00 00 1a 00  ...f............
00 00 00 00 00 01 00 00  00 50 00 00 00 00 06 03  .........P......
73 74 64 04 08 00 08 00  08 00 00 54 52 55 4e 43  std........TRUNC
41 54 45 20 54 41 42 4c  45 20 74 65 73 74 2e 74  ATE TABLE test.t
34 4a 69 9e ed                                    4Ji..

Header, 19 Bytes

• Event Time[4] = 71 17 28 5a ===> 1512576881.

• Event Type[1] = 2.

• Server_id[4] = 8c 27 00 00 ===> 10124.

• Event Size = 55 00 00 00 ===> 85.

• Next Pos = 01 09 00 00 ===> 2305.

• Flags = 00 00 => 0.

Content, Variable Data

• Thread ID[4] = 66 01 00 00 ===> 358.

• Execution Time[4] = 00 00 00 00 => 0 seconds.

• Statement default database name len[1] = 00 => 0 (no default database).

• Error code[2] = 00 00 => 0 (no errors).

• Status variable block len[2] = 1a 00 => 26.

• Status variables[n] = 00 ... 08 00.

• The default database[string] = 00 = 0 (no default database).

• The SQL statement[string] = TRUNCATE TABLE test.t4.

CRC32, 4 Bytes

• 4a 69 9e ed.

Example With Default Database and CRC32

MariaDB []> use test;
Database changed
MariaDB [test]> TRUNCATE TABLE t4;
...

ce 22 28 5a 02 8c 27 00  00 54 00 00 00 87 0c 00  ."(Z..'..T......
00 00 00 66 01 00 00 01  00 00 00 04 00 00 1a 00  ...f............
00 00 00 00 00 01 00 00  00 50 00 00 00 00 06 03  .........P......
73 74 64 04 08 00 08 00  08 00 74 65 73 74 00 54  std.......test.T
52 55 4e 43 41 54 45 20  54 41 42 4c 45 20 74 34  RUNCATE TABLE t4
08 f1 09 16                                       ....

Content, Variable Data

• Thread ID[4] = 66 01 00 00 ===> 358.

• Execution Time[4] = 10 00 00 00 => 1 second.

• Statement default database name len[1] = 04 => 4 (default database is "test").

• Error code[2] = 00 00 => 0 (no errors).

• Status variable block len[2] = 1a 00 => 26.

• Status variables[n] = 00 ... 08 00.

• The default database[string] = 74 65 73 74 00 ⇒ test.

• The SQL statement[string] = TRUNCATE TABLE test.t4.

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