Added support for detecting and handling MariaDB error 1020 “Record haschanged since last read” which occurs under REPEATABLE-READ isolationlevel when MariaDB detects that a row has changed since it was last readin the current transaction. This error is now wrapped in a newDBConsistencyError exception class that inherits fromDBDeadlock,ensuring that existing retry decorators and error handling code willautomatically handle this transient concurrency condition.

Fixed handling of MariaDB error 1020 that was previously not properlycategorized by oslo.db’s exception filtering system. This error, whichcan occur in OpenStack services like Nova and Keystone when using MariaDBwith REPEATABLE-READ isolation level, is now properly wrapped in aDBConsistencyError exception (a subclass ofDBDeadlock) insteadof being passed through as a genericOperationalError. This ensuresthat existing retry mechanisms that handle deadlock-like conditions willautomatically work with this MariaDB-specific consistency error.

For more details, seebug 2116186.