A way to run non-transactional DDL commands / PG requires autocommit to modify a type ?!

Migrated issue, originally created by Wichert Akkerman (@wichert)

Unfortunately not all DDL commands for PostgreSQL can be used in a transaction. I ran into this when trying to add a new value to an enum:

db=# BEGIN;
BEGIN
db=# ALTER TYPE article_type ADD VALUE 'unknown';
ERROR:  ALTER TYPE ... ADD cannot run inside a transaction block

I’m not sure what the best way to handle this is in alembic currently. Perhaps do op.execute('COMMIT') manually? Perhaps alembic needs an in-between-commit operation for this.

[sqlalchemy-bot]

Wichert Akkerman (@wichert) wrote:

Looks like psycopg2 doesn’t do that here for some reason. This code ran without problems:

op.execute('COMMIT')  # See https://bitbucket.org/zzzeek/alembic/issue/123
op.execute('ALTER TYPE article_type ADD VALUE \'unknown\'')

[sqla-tester]

Mike Bayer has proposed a fix for this issue in the master branch:

Add autocommit_block https://gerrit.sqlalchemy.org/1463