How fast growing undo logs impact MySQL performance?
Growing undo logs can impact MySQL performance in several ways:
- Increased disk space usage: As undo logs grow, they consume more disk space, which can lead to disk space issues, such as running out of disk space or slow disk I/O.
- Increased memory usage: The undo logs need to be kept in memory to ensure quick access during rollbacks, so as they grow, they consume more memory, which can lead to increased pressure on the buffer pool and cause the MySQL server to use more swap space.
- Increased contention: As undo logs grow, more undo logs are created and reused, which can lead to increased contention and lock waits, which can slow down the performance of the MySQL server.
- Increased checkpoint activity: As undo logs grow, more undo logs need to be checkpointed, which increases the workload of the background writer thread and can slow down the performance of the MySQL server.
- Increased rollback time: In the event of a rollback, the MySQL server needs to read the undo logs, so as they grow, the rollback process takes longer, which can slow down the performance of the MySQL server.
from mysql.connector import errorcode
# Connect to MySQL
cnx = mysql.connector.connect(user='username', password='password', host='hostname', database='performance_schema')
# Execute the query to retrieve undo log information from the performance_schema
cursor = cnx.cursor()
query = "SELECT * FROM performance_schema.undo_log ORDER BY undo_log_id"
# Print the results
print("UNDO LOG INFORMATION")
print("ID \t\t\t\t\t SIZE \t\t\t\t\t CREATED")
for row in cursor:
print(row, "\t\t\t\t\t", row, "\t\t\t\t\t", row)
# Close the cursor and connection
query = "SELECT * FROM performance_schema.undo_log_stats"
query = "SET GLOBAL performance_schema = ON"