Fix db migrate failure to Airflow 2.9.2 under PyMySQL driver - #70235
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Fix db migrate failure to Airflow 2.9.2 under PyMySQL driver#70235Aaryan123456679 wants to merge 3 commits into
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Upgrading through revision 686269002441 raised pymysql.err.ProgrammingError because the migration used MySQL's PREPARE/EXECUTE/DEALLOCATE PREPARE dynamic SQL to conditionally drop unique constraints, which PyMySQL's driver does not support (see PyMySQL/PyMySQL#202). Replaced with a plain lookup of existing constraints from information_schema.TABLE_CONSTRAINTS followed by conditional ALTER TABLE ... DROP INDEX statements, which works with any MySQL driver. Verified against a real MySQL/PyMySQL backend: downgrading to bff083ad727d and re-running db migrate now completes without error. closes: apache#43690
The PyMySQL online-mode fix in this migration queries information_schema.TABLE_CONSTRAINTS via conn.execute() to decide which legacy unique constraints to drop. In Alembic's offline (--sql) mode there is no live connection, so conn.execute() returns None and iterating over it raises TypeError, breaking the CI "Test offline migration" step. Guard the query-then-conditionally-drop logic behind context.is_offline_mode(), falling back to the original dynamic prepare/execute/deallocate SQL text for the offline branch, since that text is only ever emitted as script output there rather than executed directly.
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Migrating the metadata database to Airflow 2.9.2 (revision
686269002441) raisedpymysql.err.ProgrammingErroron MySQL when using the PyMySQL driver, because the migration used MySQL'sPREPARE/EXECUTE/DEALLOCATE PREPAREdynamic SQL to conditionally drop unique constraints on theconnectionanddag_runtables. This syntax is not supported by PyMySQL (see PyMySQL#202), so any deployment using PyMySQL as its MySQL driver could not migrate past this revision.Replaced the dynamic SQL with a plain lookup of existing constraints from
information_schema.TABLE_CONSTRAINTS, followed by conditionalALTER TABLE ... DROP INDEXstatements — this works with any MySQL driver.Verified against a real MySQL backend forced to use
mysql+pymysql://: downgrading tobff083ad727dand re-runningairflow db migratenow completes without error, and the expected unique constraints (connection_conn_id_uq,dag_run_dag_id_*_key) are present afterward.closes: #43690
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