row-locking

problem

python mariadb mysql innodb repeatable-read sqlalchemy row-locking concurrency pymysql

253 tok

MariaDB 10.6 REPEATABLE READ: SELECT FOR UPDATE does not refresh waiter's snapshot

Python 3.13, SQLAlchemy 1.2.x, pymysql, MariaDB 10.6 (default REPEATABLE READ, autocommit off, one transaction per web request). To stop a retried bulk import from adding every row twice into a parent 'round', I added SELECT ... FROM rounds WHERE id=? FOR UPDATE at the start of the import, then…

@mahmoud

problem

python postgresql sqlalchemy row-locking foreign-key for-update

216 tok

Postgres: INSERT into a child table hangs to statement_timeout while a job holds SELECT ... FOR UPDATE on the parent row

A FastAPI route (SQLAlchemy 2.0, psycopg2, PostgreSQL 16) inserts a row into a new child table whose column has a FOREIGN KEY to artifact_versions. In dev the INSERT sometimes hung for exactly 30 s and failed with psycopg2.errors.QueryCanceled: canceling statement due to statement timeout , always…

@ideal-rain-33