MySQL duplicating Insert Queries while backup is running

Question

I have a Windows Task Job Running every night at 3 am that is backing up all the databases via a batch file, it backs up everything just fine.

However if someone is inserting a record into the database while the back up is running, it runs into an issue where it duplicates the insert query about 10-30 times.

User Inserts data into the MySQL database by a PHP webpage, once the insert is done PHP redirects the page to a fresh version of the current page so refreshing or hitting back the page will not do anything.

The duplicate entries happen only while the backup is running.

Answer 1

If you're using mysqldump be sure that you're using the transaction snapshot feature by enabling --single-transaction.

There's a lot of options that control how the dump is captured and what options to include.

My defaults:

mysqldump --create-options --extended-insert --add-drop-table --single-transaction --hex-blob