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I am trying to do schema migration in PostgreSQL via Alembic.

Following this question Undo last alembic migration

I have 2 migrations with:

revision = '0eb4bd9decb0',down_revision = None
--and 
revision = 'bf34bf428845' ,down_revision = '0eb4bd9decb0'

So I am successfully run migrations from both migration files by:

alembic upgrade 0eb4bd9decb0    
alembic upgrade bf34bf428845

Now I have a problem in Downgrading these migration i.e I want to downgrade migration with revision= 'bf34bf428845'

so I write:

alembic downgrade bf34bf428845

But It is not Working and not showing any error

Output of above code:

(migration) C:\xampp\htdocs\dbmigration python\migration\db>alembic downgrade bf34bf428845
INFO  [alembic.runtime.migration] Context impl PostgresqlImpl.
INFO  [alembic.runtime.migration] Will assume transactional DDL.

but if I run this code:

alembic downgrade -1

It is working as expected as per by Undo last Alembic migration

My question:

How can I downgrade alembic migration by revision id?

Anurag Dabas
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    What happens if you do `alembic downgrade 0eb4bd9decb0` ? – Gord Thompson Jul 11 '21 at 11:51
  • @GordThompson Sir when I run `alembic downgrade 0eb4bd9decb0` then It will downgrade `bf34bf428845` i.e my table is truncated(I write that in function downgrade in `bf34bf428845`) – Anurag Dabas Jul 16 '21 at 08:19

1 Answers1

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When you run

alembic upgrade 0eb4bd9decb0
alembic upgrade bf34bf428845

which, by the way, is the same as just

alembic upgrade bf34bf428845

your database will be at revision bf34bf428845. Then if you run

alembic downgrade bf34bf428845

it will have no effect because the database is already at revision bf34bf428845.

If you want to undo the changes that brought you to revision bf34bf428845 you need to downgrade to the revision before bf34bf428845, i.e.,

alembic downgrade bf34bf428845-1

or

alembic downgrade 0eb4bd9decb0
Gord Thompson
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