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"""Change ``task_instance.task_duration`` type to ``FLOAT``

Revision ID: 2e541a1dcfed
Revises: 1b38cef5b76e
Create Date: 2015-10-28 20:38:41.266143

"""

import sqlalchemy as sa
from alembic import op
from sqlalchemy.dialects import mysql

# revision identifiers, used by Alembic.
revision = '2e541a1dcfed'
down_revision = '1b38cef5b76e'
branch_labels = None
depends_on = None
airflow_version = '1.6.0'


def upgrade():
    # use batch_alter_table to support SQLite workaround
    with op.batch_alter_table("task_instance") as batch_op:
        batch_op.alter_column(
            'duration',
            existing_type=mysql.INTEGER(display_width=11),
            type_=sa.Float(),
            existing_nullable=True,
        )


def downgrade():
    pass
