QUERY_EVENT

This event is written into the binary log file for:

• STATEMENT based replication (updating statements)
• DDLs
• COMMIT related to non transactional engines (MyISAM, BLACKHOLE etc)

Header

• Event Type = 0x02

Fields

Fixed data part:

Variable data part:

• byte<n> 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<NUL> The default database name (null-terminated).
• string<EOF> The SQL statement. By subtraction the size of the statement can be known.

Status variables

Q_FLAGS2_CODE (0x00):

• uint<4> bitmask

Q_SQL_MODE_CODE (0x01):

• uint<8> 8-byte bitmask

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<length> time zone

Q_CATALOG_NZ_CODE (0x06):

• uint<1> length
• string<length> 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 anymore

• uint<4> original event length

Q_INVOKER (0x0B|):

• uint<1> user name length
• string<length> user name
• uint<1> host name length
• string<length> host name

Q_UPDATED_DB_NAMES (0x0C): MySQL only

• uint<1> count
• for (i=0;i < count; i++)
  • string<NULL> 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 db)
• 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<NUL>] = 00 = 0 (no default db)
• The SQL statement[string<EOF>] = TRUNCATE TABLE test.t4

CRC32, 4 Bytes

• 4a 69 9e ed

Example With Default db 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 db 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<NUL>] = 74 65 73 74 00 =>test
• The SQL statement[string<EOF>] = TRUNCATE TABLE test.t4