can you provide SQLAlchemy statement output please, set "level = INFO"
under [logger_sqlalchemy] in alembic.ini
op.alter_column() does not emit DELETE and nothing in Alembic emits
the DELETE statement anywhere except upon the alembic_version table
itself.
On Mon, Oct 8, 2018 at 10:31 AM Richard <goo...@richard.do> wrote:
>
> I'm using postgres version 10, alembic 1.0.0, sqlalchemy 1.2.12. I'm aware
> ALTER COLUMN in SQL doesn't delete rows, but op.alter_column is doing that.
>
> My customer & daily reading models look like:
>
>
> class Customer(DeclarativeBase):
> __tablename__ = 'customers'
> id = Column(Integer, primary_key=True)
> electricity_readings = relationship(
> 'ElectricityMeterReading', cascade='all,delete-orphan',
> backref=backref('customer', cascade='all')
> )
> gas_readings = relationship(
> 'GasMeterReading', cascade='all,delete-orphan',
> backref=backref('customer', cascade='all')
> )
> daily_smart_meter_readings = relationship(
> 'DailyMeterReading',
> cascade='all,delete-orphan',
> backref=backref('customer', cascade='all')
> )
>
> class DailyMeterReading(DeclarativeBase):
> __tablename__ = 'daily_smart_meter_readings'
> id = Column(Integer, primary_key=True)
> customer_pk = Column(
> Integer, ForeignKey('customers.id'), nullable=False, index=True
> )
> reading = Column(Float, nullable=False)
> reading_at = Column(UtcDateTime, nullable=False, index=True)
>
>
>
>
>
>
>
> On Monday, October 8, 2018 at 3:26:11 PM UTC+1, Mike Bayer wrote:
>>
>> Hi there -
>>
>> I have no idea what you are seeing. an actual ALTER COLUMN
>> operation does not delete rows. Of course, if you are using SQLite
>> and batch mode, that might affect things, but you have not specified
>> this. Please specify complete information including log output,
>> stack traces, database in use, sample schema, etc.
>>
>> On Mon, Oct 8, 2018 at 9:36 AM Richard <goo...@richard.do> wrote:
>> >
>> >
>> > Note that if I do the same op.alter_column on another table which has a
>> > customer FK, it works fine and does not delete all the rows.
>> >
>> > On Monday, October 8, 2018 at 1:50:38 PM UTC+1, Richard wrote:
>> >>
>> >> I have an alembic migration which renames a FK column on a table from
>> >> 'customer_id' to 'customer_pk'.
>> >>
>> >> I used to have more in the migration file but narrowed it down to this
>> >> code causing all the rows to be deleted.
>> >>
>> >> def upgrade():
>> >> op.alter_column(
>> >> 'daily_smart_meter_readings', column_name='customer_id',
>> >> new_column_name='customer_pk',
>> >> )
>> >>
>> >>
>> >> I'm using alembic==1.0.0 and Python 3.6.4.
>> >>
>> >> Is there something wrong with the above code or is this a bug in the
>> >> library?
>> >>
>> >> Thanks
>> >
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