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How to switch to native versioning with existing version tables?

See original GitHub issue

Hi there, I have a big project which has been using sqlalchemy-continuum for a long time. I’m trying to switch to use native versioning so we can do bulk imports and still get versions.

I set the native_versioning option:

    options={'native_versioning': True}

And then ran an alembic migration calling sync_trigger for all the version tables:

conn = op.get_bind()
sync_trigger(conn, 'user_version')
sync_trigger(conn, 'inventory_item_version')

I can see in the database that _audit triggers are created for all the tables. However, my tests now always return a length of 0 for list(model.versions) after updating a model. Am I missing a step?

Issue Analytics

  • State:open
  • Created 2 years ago
  • Reactions:1
  • Comments:5 (2 by maintainers)

github_iconTop GitHub Comments

evryscommented, Mar 19, 2022

I ended up getting it to work by recreating the transaction table with native_versioning enabled and then copying all the old transactions across. I also needed to enable the hstore extension, and fork sqlalchemy-continuum to change a boolean so it no longer assumed the presence of PropertyModTrackerPlugin.

I should make a PR adding some documentation about it and fixing the mod tracker thing. In the meantime this is the migration I used, if someone else encounters this issue:

conn = op.get_bind()

# Enable hstore extension (used by versioning triggers)

# Rename our existing transaction table out of the way
op.execute("ALTER TABLE transaction RENAME CONSTRAINT transaction_pkey TO old_transaction_pkey")
op.execute("ALTER TABLE transaction RENAME CONSTRAINT transaction_user_id_fkey TO old_transaction_user_id_fkey")
op.execute("ALTER INDEX ix_transaction_user_id RENAME TO old_ix_transaction_user_id")
op.execute("ALTER TABLE transaction RENAME TO old_transaction;")
op.execute("ALTER SEQUENCE transaction_id_seq RENAME TO old_transaction_id_seq;")

# Make a new transaction table (this adds a particular trigger needed for
# native_versioning to work)
Transaction = db.Model._decl_class_registry.get('Transaction')

# Copy our data across
op.execute("INSERT INTO transaction SELECT * FROM old_transaction;")
op.execute("DROP TABLE old_transaction;")

# Restore the old id sequence
op.execute("DROP SEQUENCE transaction_id_seq;")
op.execute("ALTER SEQUENCE old_transaction_id_seq RENAME TO transaction_id_seq;")

# Create all the versioning update triggers
sync_trigger(conn, 'user_version')
sync_trigger(conn, 'inventory_item_version')
guzzijonescommented, May 26, 2022

Postgres database server version 14 also requires quotes around the version_table_name_format if your table name has capital letters.

sync_trigger(ob.get_bind(), 'mytable_version',
Read more comments on GitHub >

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