"""add batch_id to processing_tasks

批次 2（D7）：批量元数据入库——processing_tasks 增加 batch_id 列，
批量任务聚合查询走 PG，替代 Redis/进程内存中的批量元数据。

Revision ID: a3f8c2d91e47
Revises: 006c18c51b0d
Create Date: 2026-09-16

"""
from typing import Sequence, Union

from alembic import op
import sqlalchemy as sa


# revision identifiers, used by Alembic.
revision: str = 'a3f8c2d91e47'
down_revision: Union[str, Sequence[str], None] = '006c18c51b0d'
branch_labels: Union[str, Sequence[str], None] = None
depends_on: Union[str, Sequence[str], None] = None


def upgrade() -> None:
    op.add_column(
        'processing_tasks',
        sa.Column('batch_id', sa.String(length=36), nullable=True),
    )
    op.create_index(
        'ix_processing_tasks_batch_id',
        'processing_tasks',
        ['batch_id'],
    )


def downgrade() -> None:
    op.drop_index('ix_processing_tasks_batch_id', table_name='processing_tasks')
    op.drop_column('processing_tasks', 'batch_id')