Bug - Increase in Innodb_history_list_length

[davinc71998]

Problem

MySQL 8.0+: The value of Innodb_history_list_length steadily increases after running the program
The increase in Innodb_history_list_length is expected to have the following effects on MySQL

• Increased response time to user query

Bug description

python-mysql-replication/pymysqlreplication/binlogstream.py

Lines 638 to 655 in 62a009c

	def __get_table_information(self, schema, table):
	for i in range(1, 3):
	try:
	if not self.__connected_ctl:
	self.__connect_to_ctl()
	cur = self._ctl_connection.cursor()
	cur.execute("""
	SELECT
	COLUMN_NAME, COLLATION_NAME, CHARACTER_SET_NAME,
	COLUMN_COMMENT, COLUMN_TYPE, COLUMN_KEY, ORDINAL_POSITION,
	DATA_TYPE, CHARACTER_OCTET_LENGTH
	FROM
	information_schema.columns
	WHERE
	table_schema = %s AND table_name = %s
	ORDER BY ORDINAL_POSITION
	""", (schema, table))

According to the logic written in binlogstream.py
After executing a query through the cursor, the transaction remains in place until the program exits

the transaction is being maintained, the Innodb_history_list_length value will continue to increase when DML is performed.

Solution

After executing the query, COMMIT the transaction so that it can be terminated normally.

[dongwook-chan]

I'm glad that this issue was created and hope this issue is immediately attended. I work at Kakao which operates the most prominent messaging service in South Korea. My team integrated the python-mysql-replication for a range of applications. However, given the substantial DML traffic we handle (we have about 48m monthly active users), we observed a surge in Innodb_history_list_length, leading to challenges like delayed query responses and heightened server load.