mysqldump for AWS RDS `flush tables` error on linux only
Jan 20
I have a process that exports the data from an AWS RDS MariaDB using mysqldump which has been running succesfully in a docker-image on Concourse for years.
Since two nights ago the process has started failing with the error:
mysqldump: Couldn't execute 'FLUSH TABLES WITH READ LOCK': Access denied for user 'admin'@'%' (using password: YES) (1045)
The official AWS explanation seems to be that because they do not allow super privileges to the master user or GLOBAL READ LOCK the mysqldump fails if the --master-data option is set.
I do not have that option set. I'm running with these flags:
mysqldump -h ${SOURCE_DB_HOST} ${SOURCE_CREDENTIALS} ${SOURCE_DB_NAME} --single-transaction --compress | grep -v '^SET .*;$' > /tmp/dump.sql
mysqldump works fine when executed from my local Mac. It fails with the error that it couldn't execute FLUSH TABLES WITH READ LOCK only from the linux environment.
My question is, does anyone know how to disable the FLUSH TABLES WITH READ LOCK command in mysqldump on linux?
EDIT: Happy to accept @sergey-payu answer below as having fixed my problem, but here's a link to the MySQL bug report for the benefit of anyone else coming across this issue https://bugs.mysql.com/bug.php?id=109685
mariadb
linux1 answer
Accepted answer · original discussion
Jan 22
I faced the same issue couple of days ago. My mysqldump script had been working for years just fine until it started to give me the Access denied; you need (at least one of) the RELOAD privilege(s) for this operation error. My first instinct was to grant this privilege. But after that I started to get Access denied for user 'user'@'%' (using password: YES) (1045) error, which is documented in AWS docs. After couple hours of investigation it turned out to be a bug of the most recent 5.7.41 version of mysql (It was released 17th of January, exactly when we started to get errors). Downgrading to 5.7.40 solved the problem. It's interesting that 5.7.41 changelog doesn't list anything close to the FLUSH TABLES WITH READ LOCK or to default values.
2 question comments
Use comments to ask for clarification. Post a solution as an answer.
Feb 28
5.7.42 / 8.0.33 releases, and here's the proposed changelog entry from the documentation team: 5.7.42: With mysqldump, using --single-transaction required either the RELOAD or FLUSH_TABLES privilege with mysqldump v5.7.41. This requirement now only applies when gtid_mode=ON (defaults to OFF) and with --set-gtid-purged = ON|AUTO (defaults to AUTO). [...]❞