MySQL Bugs: #111314: Incorrect explanation about variable max_binlog_cache

Bug #111314	Incorrect explanation about variable max_binlog_cache_size in reference manual
Submitted:	7 Jun 2023 8:38	Modified:	8 Jun 2023 21:42
Reporter:	karry zhang (OCA)	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Server: Documentation	Severity:	S3 (Non-critical)
Version:	MySQL8.0	OS:	Any
Assigned to:	Jon Stephens	CPU Architecture:	Any

Description:
The explanation of parameter max_binlog_cache_size in the user manual is as follows:

If a transaction requires more than this many bytes of memory, the server generates a Multi-statement transaction required more than 'max_binlog_cache_size' bytes of storage error.

However, we know that the parameter max_binlog_cache_size actually represents the upper limit of the binlog cache, but the contents of the binlog cache will not be completely stored in memory, and the content exceeding the specified size of binlog_cache_size will be stored in a temporary file. 

This explanation of reference manual will confuse users that max_binlog_cache_size is a limit on the memory used by transactions, but it is not the case.

How to repeat:
You can see the explanation about max_binlog_cache_size in reference manual.

https://dev.mysql.com/doc/refman/8.0/en/replication-options-binary-log.html#sysvar_max_bin...

Suggested fix:
I believe that the following explanation is more accurate:

If a transaction requires more than this many bytes, the server generates a Multi-statement transaction required more than 'max_binlog_cache_size' bytes of storage error.

Hello karry zhang,

Thank you for the report and feedback.

regards,
Umesh

Fixed in all versions of the MySQL Manual, in mysqldoc rev 75864.

The changes should be visible on the website soon.

Thanks!