Files
youclonedl/backend/database.py
Mattias Tall 74e9a52096 Fix Following page: replace 9-subquery-per-channel stats with 2 CTEs + indexes
The old _CHANNEL_STATS_SELECT ran 9 correlated subqueries for each
channel row. With 1266 channels that was ~11000 sub-executions per
GET /channels request, causing multi-second (or timeout) delays.

New approach: 2 CTEs (vinfo for counts/sums, nc for new_count) each do
a single aggregated pass over all followed-channel videos, joined back
to channels. Only 2 correlated LIMIT-1 subqueries remain for
latest_video_id/title (fast with the new index).

Also adds 4 indexes on startup (IF NOT EXISTS — safe to deploy):
- videos(channel_id, published_at DESC)  — latest video lookups
- videos(channel_id, indexed_at)         — new_count filter
- user_videos(video_id, user_id)         — watch/download aggregation
- user_channels(user_id, status)         — followed channel filter

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
2026-05-26 16:04:41 +02:00

116 lines
4.0 KiB
Python

from sqlalchemy import create_engine, event, text
from sqlalchemy.orm import sessionmaker, DeclarativeBase
from .config import settings
engine = create_engine(
settings.database_url,
connect_args={"check_same_thread": False},
echo=False,
)
@event.listens_for(engine, "connect")
def set_sqlite_pragma(dbapi_conn, _):
cursor = dbapi_conn.cursor()
cursor.execute("PRAGMA journal_mode=WAL")
cursor.execute("PRAGMA foreign_keys=ON")
cursor.execute("PRAGMA busy_timeout=5000")
cursor.execute("PRAGMA synchronous=NORMAL")
cursor.close()
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
class Base(DeclarativeBase):
pass
FTS_SETUP_SQL = """
CREATE VIRTUAL TABLE IF NOT EXISTS videos_fts USING fts5(
title, description, content=videos, content_rowid=id
);
CREATE VIRTUAL TABLE IF NOT EXISTS channels_fts USING fts5(
name, description, content=channels, content_rowid=id
);
CREATE TRIGGER IF NOT EXISTS videos_ai AFTER INSERT ON videos BEGIN
INSERT INTO videos_fts(rowid, title, description)
VALUES (new.id, new.title, COALESCE(new.description, ''));
END;
CREATE TRIGGER IF NOT EXISTS videos_ad AFTER DELETE ON videos BEGIN
INSERT INTO videos_fts(videos_fts, rowid, title, description)
VALUES ('delete', old.id, old.title, COALESCE(old.description, ''));
END;
CREATE TRIGGER IF NOT EXISTS videos_au AFTER UPDATE ON videos BEGIN
INSERT INTO videos_fts(videos_fts, rowid, title, description)
VALUES ('delete', old.id, old.title, COALESCE(old.description, ''));
INSERT INTO videos_fts(rowid, title, description)
VALUES (new.id, new.title, COALESCE(new.description, ''));
END;
CREATE TRIGGER IF NOT EXISTS channels_ai AFTER INSERT ON channels BEGIN
INSERT INTO channels_fts(rowid, name, description)
VALUES (new.id, new.name, COALESCE(new.description, ''));
END;
CREATE TRIGGER IF NOT EXISTS channels_ad AFTER DELETE ON channels BEGIN
INSERT INTO channels_fts(channels_fts, rowid, name, description)
VALUES ('delete', old.id, old.name, COALESCE(old.description, ''));
END;
CREATE TRIGGER IF NOT EXISTS channels_au AFTER UPDATE ON channels BEGIN
INSERT INTO channels_fts(channels_fts, rowid, name, description)
VALUES ('delete', old.id, old.name, COALESCE(old.description, ''));
INSERT INTO channels_fts(rowid, name, description)
VALUES (new.id, new.name, COALESCE(new.description, ''));
END;
"""
def _add_column_if_missing(raw_conn, table: str, column: str, definition: str):
existing = {row[1] for row in raw_conn.execute(f"PRAGMA table_info({table})")}
if column not in existing:
raw_conn.execute(f"ALTER TABLE {table} ADD COLUMN {column} {definition}")
def init_db():
from . import models # noqa: F401
Base.metadata.create_all(bind=engine)
raw_conn = engine.raw_connection()
try:
# Column migrations — safe to run on every startup
_add_column_if_missing(raw_conn, "videos", "view_count", "INTEGER")
_add_column_if_missing(raw_conn, "videos", "like_count", "INTEGER")
_add_column_if_missing(raw_conn, "videos", "dislike_count", "INTEGER")
raw_conn.commit()
# Indexes that make the channel-stats CTE query fast with many channels
for idx_sql in [
"CREATE INDEX IF NOT EXISTS idx_videos_channel_published ON videos(channel_id, published_at DESC)",
"CREATE INDEX IF NOT EXISTS idx_videos_channel_indexed ON videos(channel_id, indexed_at)",
"CREATE INDEX IF NOT EXISTS idx_user_videos_video_user ON user_videos(video_id, user_id)",
"CREATE INDEX IF NOT EXISTS idx_user_channels_user_status ON user_channels(user_id, status)",
]:
try:
raw_conn.execute(idx_sql)
except Exception:
pass
raw_conn.commit()
# executescript handles multi-statement SQL including trigger BEGIN...END blocks
raw_conn.executescript(FTS_SETUP_SQL)
finally:
raw_conn.close()
def get_db():
db = SessionLocal()
try:
yield db
finally:
db.close()