CREATE INDEX (possibly other constraints, need to test) missing when table is dropped in the upgrade

[sqlalchemy-bot]

Migrated issue, originally created by Michael Bayer (@zzzeek)

Step 1, env.py:

from sqlalchemy import *

target_metadata = m = MetaData()

Table(
    'a', m, Column('id', Integer, primary_key=True),
    Column('q', Integer, index=True)
)

step 2:

#!

[classic@photon2 alembic]$ PYTHONPATH=~/dev/sqlalchemy/lib/ python -m alembic.config revision -m "rev1" --autogenerate
INFO  [alembic.runtime.migration] Context impl MySQLImpl.
INFO  [alembic.runtime.migration] Will assume non-transactional DDL.
INFO  [alembic.autogenerate.compare] Detected added table 'a'
INFO  [alembic.autogenerate.compare] Detected added index 'ix_a_q' on '['q']'
  Generating /home/classic/dev/alembic/foo/versions/54630d783fa6_rev1.py ... done
[classic@photon2 alembic]$ PYTHONPATH=~/dev/sqlalchemy/lib/ python -m alembic.config upgrade head
INFO  [alembic.runtime.migration] Context impl MySQLImpl.
INFO  [alembic.runtime.migration] Will assume non-transactional DDL.
INFO  [alembic.runtime.migration] Running upgrade  -> 54630d783fa6, rev1

migration file has:

def upgrade():
    # ### commands auto generated by Alembic - please adjust! ###
    op.create_table('a',
    sa.Column('id', sa.Integer(), nullable=False),
    sa.Column('q', sa.Integer(), nullable=True),
    sa.PrimaryKeyConstraint('id')
    )
    op.create_index(op.f('ix_a_q'), 'a', ['q'], unique=False)
    # ### end Alembic commands ###


def downgrade():
    # ### commands auto generated by Alembic - please adjust! ###
    op.drop_index(op.f('ix_a_q'), table_name='a')
    op.drop_table('a')
    # ### end Alembic commands ###

now remove the table:

from sqlalchemy import *

target_metadata = m = MetaData()

#Table(
#    'a', m, Column('id', Integer, primary_key=True),
#   Column('q', Integer, index=True)
#)

run again:

[classic@photon2 alembic]$ PYTHONPATH=~/dev/sqlalchemy/lib/ python -m alembic.config revision -m "rev2" --autogenerate
INFO  [alembic.runtime.migration] Context impl MySQLImpl.
INFO  [alembic.runtime.migration] Will assume non-transactional DDL.
INFO  [alembic.autogenerate.compare] Detected removed table u'a'
  Generating /home/classic/dev/alembic/foo/versions/d8d7ee4f2f3b_rev2.py ... done

migration file is missing the index:

def upgrade():
    # ### commands auto generated by Alembic - please adjust! ###
    op.drop_table('a')
    # ### end Alembic commands ###


def downgrade():
    # ### commands auto generated by Alembic - please adjust! ###
    op.create_table('a',
    sa.Column('id', mysql.INTEGER(display_width=11), nullable=False),
    sa.Column('q', mysql.INTEGER(display_width=11), autoincrement=False, nullable=True),
    sa.PrimaryKeyConstraint('id'),
    mysql_default_charset=u'utf8',
    mysql_engine=u'InnoDB'
    )
    # ### end Alembic commands ###

we need to generate MigrateTableOps for tables that are removed during autogenerate.

[sqlalchemy-bot]

Michael Bayer (@zzzeek) wrote:

https://gerrit.sqlalchemy.org/#/c/zzzeek/alembic/+/641

[sqlalchemy-bot]

Michael Bayer (@zzzeek) wrote:

Detect indexes for table that's dropped

Fixed bug where the indexes would not be included in a
migration that was dropping the owning table. The fix
now will also emit DROP INDEX for the indexes ahead of time,
but more importantly will include CREATE INDEX in the
downgrade migration.

Change-Id: I15852bf1cca6de26dd6e7e5ede69bc9e2145c5c0
Fixes: #468

→ 058b2eb

[sqlalchemy-bot]

Changes by Michael Bayer (@zzzeek):

• changed status to closed