52 lines
2.1 KiB
Python
52 lines
2.1 KiB
Python
"""2026070902_add_generated_date_expression_indexes
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Revision ID: 2026070902
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Revises: 2026070901
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Create Date: 2026-07-09 00:00:00.000000
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该文件包含 2026-07-09 的数据库迁移内容：
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1. chat_generation_tasks 表增加 generated_at 日期表达式索引，优化按日期分组/筛选
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2. generation_records 表增加 generated_at 日期表达式索引，优化按日期分组/筛选
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"""
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from typing import Sequence, Union
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from alembic import op
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import sqlalchemy as sa
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revision: str = '2026070902'
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down_revision: Union[str, None] = '2026070901'
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branch_labels: Union[str, Sequence[str], None] = None
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depends_on: Union[str, Sequence[str], None] = None
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def upgrade() -> None:
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# ========================================
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# 2026-07-09 - 生成记录表增加日期表达式索引
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# ========================================
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# 使用 CAST(timezone('utc', generated_at) AS date) 而不是 date(generated_at)：
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# 1) 当 generated_at 为 timestamptz 时，date() 的结果依赖会话时区，属于 STABLE 函数，
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# 无法用于索引表达式。显式指定 UTC 时区后转为 date 是纯计算，属于 IMMUTABLE。
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# 2) 必须用 CAST(... AS date) 而不能用 ::date：:: 的优先级高于函数调用，
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# PG 会把 func(x)::date 解析为 func(x::date)，导致语法错误。
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op.create_index(
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'idx_chat_generation_tasks_generated_date',
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'chat_generation_tasks',
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[sa.text("CAST(timezone('utc', generated_at) AS date)")],
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unique=False,
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)
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op.create_index(
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'idx_generation_records_generated_date',
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'generation_records',
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[sa.text("CAST(timezone('utc', generated_at) AS date)")],
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unique=False,
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)
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def downgrade() -> None:
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# ========================================
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# 2026-07-09 - 生成记录表增加日期表达式索引（回滚）
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# ========================================
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op.drop_index('idx_generation_records_generated_date', table_name='generation_records')
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op.drop_index('idx_chat_generation_tasks_generated_date', table_name='chat_generation_tasks')
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