AgentSkillsCN

N+1 Query Detection

在 GORM 仓储层与服务层代码中检测 N+1 查询模式——识别出频繁执行查询的循环、遗漏的预加载操作，以及无上限的批量查询。

SKILL.md
--- frontmatter
name: N+1 Query Detection
description: Detect N+1 query patterns in GORM repository and service code — identify loops that execute queries, missing preloads, and unbounded fetches
category: performance
version: 1.0.0
triggers:
  - repository-change
  - service-change
  - performance-review
globs: "**/repository/**,**/service/**"

N+1 Query Detection Skill

Scan repository and service code for N+1 query patterns that cause performance degradation.

Trigger Conditions

  • •Repository or service files are modified
  • •Performance review is requested
  • •New data access patterns are introduced
  • •User invokes with "N+1 check" or "n-plus-1-query-detection"

Input Contract

  • •Required: Path to repository and/or service files
  • •Optional: GORM configuration for preload analysis

Output Contract

  • •List of N+1 patterns found with file:line references
  • •Severity assessment (critical for high-volume paths, low for admin-only)
  • •Fix recommendation (Preload, Joins, or batch query)
  • •Unbounded query warnings (missing Limit)

Tool Permissions

  • •Read: Repository files, service files, model relationship definitions
  • •Write: None (read-only analysis)
  • •Search: Grep for loop patterns, .Find(), .First(), relationship access

Execution Steps

  1. •Scan for loops with queries: Find patterns where a database query is inside a for loop
  2. •Check preloads: For each query that accesses relationships, verify Preload() or Joins() is used
  3. •Check unbounded queries: Find .Find() calls without .Limit() on list endpoints
  4. •Assess severity: Rate each finding by the expected data volume (high-traffic endpoints are critical)
  5. •Recommend fixes: Suggest specific GORM patterns (Preload, Joins, SelectinLoad)
  6. •Report: Produce findings with code examples for the fix

Common Patterns (Anti-patterns)

go
// N+1: Query inside loop
users, _ := db.Find(&users)
for _, u := range users {
    db.Where("user_id = ?", u.ID).Find(&orders) // N+1!
}

// Fix: Preload
db.Preload("Orders").Find(&users)

References

  • •.cursor/rules/122-gorm-conventions.mdc
  • •.cursor/rules/047-performance-optimization.mdc