Undolog Packet for query is too large when table longblob field more than 40MB

[jsbxyyx]

• I have searched the issues of this repository and believe that this is not a duplicate.

Ⅰ. Issue Description

Packet for query is too large (83,886,137 > 67,108,864). You can change this value on the server by setting the 'max_allowed_packet' variable.

create table test (
id int primary key,
name varchar(45),
file longblob
)

insert into test(id, name file) values(1, 'name', '<binary 40MB>');

update test set file = '<binary 40MB>', name = 'name2' where id = 1;

Ⅱ. Describe what happened

If there is an exception, please attach the exception trace:

Just paste your stack trace here!

Ⅲ. Describe what you expected to happen

Ⅳ. How to reproduce it (as minimally and precisely as possible)

1. xxx
2. xxx
3. xxx

Minimal yet complete reproducer code (or URL to code):

Ⅴ. Anything else we need to know?

Ⅵ. Environment:

• JDK version(e.g. java -version):
• Seata client/server version:
• Database version:
• OS(e.g. uname -a):
• Others:

[slievrly]

From what I see, the issue described is a solution. The default value for max_allowed_packet is 64M, yet you're describing storage of 40M, which seems to have some gap. Additionally, is the oversized transaction mentioned in the issue something encountered in a real-world scenario?

[jsbxyyx]

场景：通过数据库来保存附件。
Scenes：Save attachments through database.

更新语句时，前置镜像 + 后置镜像 > 64MB
before image + after image > 64MB, when update

[leizhiyuan]

Storing attachments in a database is not a good practice. It is recommended to use object storage instead. The database stores the address of the storage location.
数据库保存附件不是一个好的实践，建议自己走对象存储。数据库存储地址