max_allowed_packet和slave_max_allowed_packet

igoodful@10.10.10.10 ((none)) > show global variables like '%max_allowed_packet%';
+--------------------------+------------+
| Variable_name            | Value      |
+--------------------------+------------+
| max_allowed_packet       | 67108864   |
| slave_max_allowed_packet | 1073741824 |
+--------------------------+------------+
2 rows in set (0.00 sec)

Tue Jun 23 16:05:04 2020
igoodful@10.10.10.10  ((none)) > select 67108864/1024/1024;
+--------------------+
| 67108864/1024/1024 |
+--------------------+
|        64.00000000 |
+--------------------+
1 row in set (0.00 sec)

Tue Jun 23 16:05:20 2020
igoodful@10.10.10.10  ((none)) > select 1073741824/1024/1024;
+----------------------+
| 1073741824/1024/1024 |
+----------------------+
|        1024.00000000 |
+----------------------+
1 row in set (0.00 sec)

Tue Jun 23 16:09:09 2020
igoodful@10.10.10.10  ((none)) >

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max_allowed_packet变量一般线上设置成64M，过小容易造成批量插入语句执行失败。

slave_max_allowed_packet变量一般设置成1G，过小容易造成复制失败