Twice recently, on two different PostgreSQL 9.5 databases hosted at Amazon RDS, we've been unable to apply Alembic migrations. We have successfully run dozens of Alembic migrations in the past against one of these databases but those were quieter times for us. As far as I can tell, it's because our databases are too busy now and the load never lets up.
The Alembic process just hangs and other database queries start backing up. The only recourse is to kill the Alembic process. In at least one case, we've also had to track down the ALTER statement in pg_stat_activity and terminate the associated pid. Once I had to reboot the database at RDS before it recovered. The SQL generated for one of these migrations is: ALTER TABLE redacted ADD COLUMN report_format VARCHAR(4) which is as simple as it gets. In both cases, we're trying to add columns to tables that are hardly ever modified—and not at all while the Alembic migrations were executing. However, many of our most frequent SELECTs JOIN to these tables, so they're constantly being read from. Aside, from making a planned outage, do we have any good options? Thanks! /George Reilly -- SQLAlchemy - The Python SQL Toolkit and Object Relational Mapper http://www.sqlalchemy.org/ To post example code, please provide an MCVE: Minimal, Complete, and Verifiable Example. See http://stackoverflow.com/help/mcve for a full description. --- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
