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ORM Traps
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2026/3/9
- Iterating QuerySet twice hits DB twice — `list(qs)` to cache - `exists()` vs `bool(qs)` — bool fetches all rows, exists() is O(1) - `count()` vs `len(qs)` — len() fetches all, count() uses SQL COUNT - No `select_related` in loop = N+1 — one query per FK access - `prefetch_related` after filter — invalidates cache, N+1 returns
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资源信息
- 数据来源
- bigquery-gharchive
- 分类
- data-analysis
- 创建时间
- 2026/3/9
- 更新时间
- 2026/3/14
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