infra(gsi): gsi changes

[hackmajoris]

Summary

Optimize DynamoDB single-table design by consolidating from 5 GSIs to 1 GSI, reducing infrastructure costs and complexity while maintaining query performance.

Changes

Infrastructure (deployments/app/cdk.go)

• Refactored DynamoDB table to use EntityType as partition key instead of entity_id
• Consolidated 5 Global Secondary Indexes into 1 optimized GSI (BySkill)
• Removed GSIs: SkillsByLevel, ByUser, SkillsByCategory, ByEntityType, BySkillID
• New GSI uses composite sort key pattern: SkillName (PK) + ProficiencyLevel (SK)
• Updated table structure to support entity-type-based queries on main table

Database Layer (cmd/app/internal/database/)

• Updated constants.go with new GSI name and attribute constants
• Modified user_skill_repository_dynamodb.go to use new query patterns:
  • ListUsersBySkill: Now queries BySkill GSI with SkillName partition key
  • ListUsersBySkillAndLevel: Queries BySkill GSI with skill name and proficiency level
  • ListUserSkills: Uses main table with EntityType partition key
• Removed dependencies on deprecated GSIs

Service Layer (cmd/app/internal/service/skill_service.go)

• Added new methods for cross-user skill queries:
  • ListUsersBySkill(skillName): Find all users with a specific skill
  • ListUsersBySkillAndLevel(skillName, level): Find users by skill and proficiency
• Enhanced logging for new query operations

Handler Layer (cmd/app/internal/handler/)

• Added ListUsersBySkillHandler: GET /skills/{skillName}/users
• Added ListUsersBySkillAndLevelHandler: GET /skills/{skillName}/users?level={level}
• Implemented path parameter extraction and query parameter parsing
• Added proper error handling and response formatting

Router (cmd/app/internal/router/router.go)

• Registered new cross-user skill query endpoints
• Configured JWT authentication for new routes

Benefits

• Reduced DynamoDB costs by eliminating 4 GSIs
• Simplified infrastructure maintenance
• Maintained all existing query patterns
• Added new cross-user skill discovery features
• Improved query efficiency with optimized index design

Query Pattern Support

• List all users: EntityType = "User" (main table)
• List all skills: EntityType = "Skill" (main table)
• User's skills: EntityType = "UserSkill" with entity_id prefix (main table)
• Users with skill: SkillName = "Python" (BySkill GSI)
• Users with skill at level: SkillName = "Python" AND ProficiencyLevel = "Expert" (BySkill GSI)

[amazon-q-developer]

Review Summary

This PR attempts to optimize DynamoDB design by consolidating GSIs, but contains critical blocking issues that will prevent deployment and cause runtime failures:

🚨 Critical Issues (Must Fix)

1. DynamoDB Configuration Error: The CDK configuration attempts to define multiple sort keys for a GSI, which is not supported by DynamoDB. This will cause deployment failure.

2. Query Pattern Mismatch: The database queries use 3-attribute key conditions (Category + SkillName + ProficiencyLevel) but DynamoDB only supports partition key + sort key queries.

3. Duplicate Code: There's a duplicate PutItem call in the CreateSkill method that will cause the operation to execute twice.

📋 Required Actions

1. Fix CDK GSI Configuration: Update the GSI to use only one partition key and one sort key
2. Align Query Patterns: Modify database queries to match DynamoDB's key condition limitations
3. Remove Duplicate Code: Fix the duplicate PutItem call

💡 Recommendations

Consider using a composite sort key approach where you concatenate values (e.g., SkillName#ProficiencyLevel#YearsOfExperience) as a single sort key, or use FilterExpression for additional filtering on non-key attributes.

The optimization goal is sound, but the implementation needs significant corrections to work with DynamoDB's constraints.

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