SNOW-159471 Alembic op.alter_column generates invalid SQL for rename

[ms32035]

Please answer these questions before submitting your issue. Thanks!

1. What version of Python are you using (python --version)?

3.7

2. What operating system and processor architecture are you using (python -c 'import platform; print(platform.platform())')?

3. What are the component versions in the environment (pip list)?

Package                    Version
-------------------------- ---------
alembic                    1.3.2
snowflake-connector-python 2.1.2
snowflake-sqlalchemy       1.1.17
sqlacodegen                2.1.0
SQLAlchemy                 1.3.12

4. What did you do? alembic migration with the following spec

    op.alter_column(
        "t",
        "c1",
        new_column_name="c2",
        schema="s",
    )

5. What did you expect to see?

Correctly changed table name

6. What did you see instead?

Invalid SQL: RENAME instead of RENAME COLUMN

7. Can you set logging to DEBUG and collect the logs?

sqlalchemy.exc.ProgrammingError: (snowflake.connector.errors.ProgrammingError) 001003 (42000): SQL compilation error:
syntax error line 1 at position 34 unexpected 'c1'.
[SQL: ALTER TABLE s.t RENAME c1 TO c2]

BTW, yes I know this can be worked around with op.execute

[DannyNemer]

We are seeing this issue, too. Any updates?

[sfc-gh-mkeller]

Hey people, I triaged the issue and I'm sad to say that I can't fix this for you as we don't have a snowflake-alembic package.

However, I can tell you how to fix the behaviour yourself.

Just add the following code to the class we tell you to create here: https://github.com/snowflakedb/snowflake-sqlalchemy#alembic-support

    @compiles(ColumnName)
    def visit_column_name(element, compiler, **kw):
        return "%s RENAME COLUMN %s TO %s" % (
            alter_table(compiler, element.table_name, element.schema),
            format_column_name(compiler, element.column_name),
            format_column_name(compiler, element.newname),
        )

and don't forget to:

from alembic.ddl.base import alter_table, format_column_name, ColumnName
from sqlalchemy.ext.compiler import compiles

[github-actions[bot]]

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