67 lines
2.4 KiB
Python
67 lines
2.4 KiB
Python
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"""message 补 (channel, room_id, timestamp) 索引(群聊消息窗超时修复)
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Revision ID: e6f7a8b9c0d1
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Revises: d9e0f1a2b3c4
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Create Date: 2026-09-07
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内容
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----
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群聊消息窗(/api/messages?channel=&room_id=)**刻意不带 owner**——chat_group
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按 room_id 去重后表的 owner 被最后写入的员工覆盖,与消息实际归属错位,带上
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会查空(2026-08-22 实测)。于是 ix_message_channel_owner_room_time 的
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owner 前缀用不上,优化器退化到 room 单列索引(ix_message_room)取全行再
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filter channel + filesort:
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- 16,290 条群: count 4.7s / 首页 5.1s / ASC 末页 10.7s(EXPLAIN ANALYZE
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实测,Sort row IDs 全量 16k 行、128MB buffer pool 下逐行回表磁盘随机读);
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- 真凶对话 53132846289@chatroom 40,863 条(count+首页+末页串行 ~40s),
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前端 axios 15s 超时 → 聊天记录加载失败 ECONNABORTED(2026-09-07 用户报)。
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本迁移补 (channel, room_id, timestamp) 三列索引:群查询与单聊同享
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seek + 排序直达 + 覆盖 count。模型侧 models.py 同步双声明,防 alembic
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autogenerate 反 DROP。窄列 BTREE,~94 万行在线建索引预计几十秒
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(参照 c53f90b1e6a4 实测 86 万行 16s)。
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配套:同日 /api/messages 加 order=desc + before_ts/before_id 游标参数,
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聊天窗首屏「DESC 取最新一页 + 反转」、上翻游标,避开 ASC 深 OFFSET
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逐行回表(单聊 1 万条末页实测 2.5s → DESC LIMIT 15ms)。
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幂等:``sa.inspect`` 先查同名索引,存在即跳过。SQLite/MySQL 通用。
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"""
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from collections.abc import Sequence
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import sqlalchemy as sa
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from alembic import op
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# revision identifiers, used by Alembic.
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revision: str = 'e6f7a8b9c0d1'
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down_revision: str | Sequence[str] | None = 'd9e0f1a2b3c4'
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branch_labels: str | Sequence[str] | None = None
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depends_on: str | Sequence[str] | None = None
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_INDEX_NAME = 'ix_message_channel_room_time'
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def _has_index(table: str, index: str) -> bool:
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insp = sa.inspect(op.get_bind())
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return index in {i['name'] for i in insp.get_indexes(table)}
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def upgrade() -> None:
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"""Upgrade schema."""
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if _has_index('message', _INDEX_NAME):
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return # 已建过(或先手工建过),幂等跳过
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op.create_index(
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_INDEX_NAME,
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'message',
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['channel', 'room_id', 'timestamp'],
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)
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def downgrade() -> None:
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"""Downgrade schema."""
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if not _has_index('message', _INDEX_NAME):
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return
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op.drop_index(_INDEX_NAME, table_name='message')
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