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Bug - Increase in Innodb_history_list_length #430

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Bug - Increase in Innodb_history_list_length#430
@davinc71998

Description

@davinc71998
davinc71998
opened on Aug 23, 2023

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

스크린샷 2023-08-22 오후 11 06 03

the transaction is being maintained, the Innodb_history_list_length value will continue to increase when DML is performed.
KakaoTalk_Photo_2023-08-22-23-18-38

Solution

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

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