14.9.4.6 FORMAT_DESCRIPTION_EVENT

Binlog::FORMAT_DESCRIPTION_EVENT:

A format description event is the first event of a binlog for binlog-version 4. It describes how the other events are layed out.

Note

added in MySQL 5.0.0 as replacement for START_EVENT_V3

Payload

2                binlog-version
string[50]       mysql-server version
4                create timestamp
1                event header length
string[p]        event type header lengths

Fields

• binlog-version (2) -- version of this binlog format.

• mysql-server version (string.fix_len) -- [len=50] version of the MySQL Server that created the binlog. The string is evaluted to apply work-arounds in the slave.

• create_timestamp (4) -- seconds since Unix epoch when the binlog was created

• event_header_length (1) -- length of the Binlog Event Header of next events. Should always be 19.

• event type header length (string.EOF) -- a array indexed by Binlog Event Type - 1 to extract the length of the event specific header.

Example

$ hexdump -v -s 4 -C relay-bin.000001
00000004  82 2d c2 4b 0f 02 00 00  00 67 00 00 00 6b 00 00  |.-.K.....g...k..|
00000014  00 00 00 04 00 35 2e 35  2e 32 2d 6d 32 00 00 00  |.....5.5.2-m2...|
00000024  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000034  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000044  00 00 00 00 00 00 00 82  2d c2 4b 13 38 0d 00 08  |........-.K.8...|
00000054  00 12 00 04 04 04 04 12  00 00 54 00 04 1a 08 00  |..........T.....|
00000064  00 00 08 08 08 02 00                              |........        |

For mysql-5.5.2-m2 the event specific header lengths are:

Table 14.6 Event Type Header Lengths by Binlog Version

Event Name	Header Length
	v=4	v=3	v=1
Binlog Event Header	19		13
START_EVENT_V3	56
QUERY_EVENT	13	11
STOP_EVENT	0
ROTATE_EVENT	8		0
INTVAR_EVENT	0
LOAD_EVENT	18
SLAVE_EVENT	0
CREATE_FILE_EVENT	4
APPEND_BLOCK_EVENT	4
EXEC_LOAD_EVENT	4
DELETE_FILE_EVENT	4
NEW_LOAD_EVENT	18
RAND_EVENT	0
USER_VAR_EVENT	0
FORMAT_DESCRIPTION_EVENT	84	---
XID_EVENT	0	---
BEGIN_LOAD_QUERY_EVENT	4	---
EXECUTE_LOAD_QUERY_EVENT	26	---
TABLE_MAP_EVENT	8	---
DELETE_ROWS_EVENTv0	0	---
UPDATE_ROWS_EVENTv0	0	---
WRITE_ROWS_EVENTv0	0	---
DELETE_ROWS_EVENTv1	8/6	---
UPDATE_ROWS_EVENTv1	8/6	---
WRITE_ROWS_EVENTv1	8/6	---
INCIDENT_EVENT	2	---
HEARTBEAT_EVENT	0	---
DELETE_ROWS_EVENTv2	10	---
UPDATE_ROWS_EVENTv2	10	---
WRITE_ROWS_EVENTv2	10	---

The event-size of 0x67 (103) minus the event-header length of 0x13 (19) should match the event type header length of the FORMAT_DESCRIPTION_EVENT 0x54 (84).

The number of events understood by the master may differ from what the slave supports. It is calculated by:

event-size - event-header length - 2 - 50 - 4 - 1

For mysql-5.5.2-m2 it is 0x1b (27).