Database Architect

🗄️ Database Architect Skill

2. SQLAlchemy Best Practices:

   • Use AsyncSession for all DB interactions.
   • Avoid "N+1 Problem" by using .options(selectinload/joinedload) for relationships.
   • Use declarative_base for model definitions.
   • Session Management: Use context managers (async with session:) to ensure connections close.

3. Migration Safety:

   • NEVER modify the DB schema manually. Always use Alembic.
   • Review generated migration scripts before applying.
   • migration scripts must be reversible (implement downgrade()).

4. Performance:

   • Batch Operations: Use bulk_insert_mappings or insert().values([...]) for large datasets (e.g., importing 10k candles).
   • Connection Pooling: Configure pool size and timeout correctly for the environment (Render/Local).

class TradeRepository: def init(self, session: AsyncSession): self.session = session

async def get_recent_trades(self, ticker: str, limit: int = 100) -> List[Trade]:
    # Efficient query with index usage
    stmt = (
        select(Trade)
        .where(Trade.ticker == ticker)
        .order_by(Trade.created_at.desc())
        .limit(limit)
    )
    result = await self.session.execute(stmt)
    return result.scalars().all()

</examples>

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