Parsing MySQL Binlog--(4) Table_map_event

1. Introduction

In the row format of the Binlog file, each row_event has a table_map_event that describes the internal ID and structure definition of the table.

Mysql> Show Binlog events in "mysql-bin.000002" +------------------+-----+-------------+-----------+------------ -+---------------------------------------------+| Log_name | Pos | Event_type | server_id | End_log_pos | Info |+------------------+-----+-------------+-----------+-------------+----------- ----------------------------------+|   mysql-bin.000002 | 4 |        Format_desc |         11 | 120 | Server ver:5.6.26-debug-log, Binlog ver:4 | | mysql-bin.000002 | 120 |        Query |         11 | 191 | BEGIN | | mysql-bin.000002 | 191 |        Table_map |         11 | 236 | Table_id:70 (YZS.T1) | | mysql-bin.000002 | 236 |        Write_rows |         11 | 280 | Table_id:70 Flags:stmt_end_f | | mysql-bin.000002 | 280 |        Xid |         11 | 311 | COMMIT/* xid=9 */| | mysql-bin.000002 | 311 |        Query | 11 |        382 | BEGIN | | mysql-bin.000002 | 382 |        Table_map |         11 | 427 | Table_id:70 (YZS.T1) | | mysql-bin.000002 | 427 |        Write_rows |         11 | 471 | Table_id:70 Flags:stmt_end_f | | mysql-bin.000002 | 471 |        Xid |         11 | 502 | COMMIT/* xid=37 */|+------------------+-----+-------------+-----------+-------------+----------- ----------------------------------+9 rows in Set (0.00 sec)

2. table_map_event format definition

3, combined with case description

--------Public Event Header-------

1) timestamp:62 ca A4 5a:4 bytes

2) event_type:13:1 bytes, table_map_event = 19

3) server-id:0b 00 00 00, 4 bytes, 11

4) event_size:2d 00 00 00, 4 bytes, that is, the total event size is 45 bytes

5) Next-log Ps:ec 00 00 00, 4 bytes, 236

6) flag:00 00

----------Private Event Header-------------

7) Table id:46 00 00 00 00 00, that is, the table ID is 70

8) flag:01 00, not used temporarily

----------Event Body-------------------

9) schema name length:03, that is, the schema name size is 3 bytes

) schema name:79 7a 73,yzs

11) 00

Table name length:02, which is a 2-byte size

Table Name:74 31, which is the name of T1

14) 00

Col count:02, that is, the number of columns is 2

Col type:03 03

enum enum_field_types { MYSQL_TYPE_DECIMAL, MYSQL_TYPE_TINY,              MYSQL_TYPE_SHORT,  MYSQL_TYPE_LONG,              MYSQL_TYPE_FLOAT,  MYSQL_TYPE_DOUBLE,              MYSQL_TYPE_NULL,   MYSQL_TYPE_TIMESTAMP,              MYSQL_TYPE_LONGLONG,MYSQL_TYPE_INT24,              MYSQL_TYPE_DATE,   MYSQL_TYPE_TIME,              MYSQL_TYPE_DATETIME, MYSQL_TYPE_YEAR,              MYSQL_TYPE_NEWDATE, MYSQL_TYPE_VARCHAR,              MYSQL_TYPE_BIT,              MYSQL_TYPE_TIMESTAMP2,              MYSQL_TYPE_DATETIME2,              MYSQL_TYPE_TIME2,              MYSQL_TYPE_NEWDECIMAL=246,              MYSQL_TYPE_ENUM=247,              MYSQL_TYPE_SET=248,              MYSQL_TYPE_TINY_BLOB=249,              MYSQL_TYPE_MEDIUM_BLOB=250,              MYSQL_TYPE_LONG_BLOB=251,              MYSQL_TYPE_BLOB=252,              MYSQL_TYPE_VAR_STRING=253,              MYSQL_TYPE_STRING=254,              MYSQL_TYPE_GEOMETRY=255  

(+) Col meta length:00,1 bytes

Col Meta: none

Null bitmap:02, the number of columns is 2, one byte is sufficient: 00000010, that is, the column of the primary key column cannot be null

Checksum, not in the event body. D8 B9 2b
The Write_footer function finally calculates the checksum and puts it behind the event body.

virtual bool write(IO_CACHE* file)  {    return(write_header(file, get_data_size()) ||    write_data_header(file) ||    write_data_body(file) ||    write_footer(file));  }  

# at 191  #180310 21:53:38 server id 11  end_log_pos 236 CRC32 0x2b92b9d8     

You can see the same resolution as in the Binlog file.

Parsing MySQL Binlog--(4) Table_map_event