88 lines
3.6 KiB
Markdown
88 lines
3.6 KiB
Markdown
---
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name: ck:databases
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description: Design schemas, write queries for MongoDB and PostgreSQL. Use for database design, SQL/NoSQL queries, aggregation pipelines, indexes, migrations, replication, performance optimization, psql CLI.
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license: MIT
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argument-hint: "[query or schema task]"
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metadata:
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author: claudekit
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version: "1.0.0"
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---
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# Databases Skill
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Unified guide for working with MongoDB (document-oriented) and PostgreSQL (relational) databases. Choose the right database for your use case and master both systems.
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## When to Use This Skill
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Use when:
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- Designing database schemas and data models
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- Writing queries (SQL or MongoDB query language)
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- Building aggregation pipelines or complex joins
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- Optimizing indexes and query performance
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- Implementing database migrations
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- Setting up replication, sharding, or clustering
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- Configuring backups and disaster recovery
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- Managing database users and permissions
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- Analyzing slow queries and performance issues
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- Administering production database deployments
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## Reference Navigation
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### Database Design
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- **[db-design.md](references/db-design.md)** - Activate when user requests: Database/table design for transactional (OLTP), analytics (OLAP), create or extend schema, design fact/dimension tables, analyze/review CSV/JSON/SQL files to create tables, or need advice on data storage structure.
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### MongoDB References
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- **[mongodb-crud.md](references/mongodb-crud.md)** - CRUD operations, query operators, atomic updates
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- **[mongodb-aggregation.md](references/mongodb-aggregation.md)** - Aggregation pipeline, stages, operators, patterns
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- **[mongodb-indexing.md](references/mongodb-indexing.md)** - Index types, compound indexes, performance optimization
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- **[mongodb-atlas.md](references/mongodb-atlas.md)** - Atlas cloud setup, clusters, monitoring, search
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### PostgreSQL References
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- **[postgresql-queries.md](references/postgresql-queries.md)** - SELECT, JOINs, subqueries, CTEs, window functions
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- **[postgresql-psql-cli.md](references/postgresql-psql-cli.md)** - psql commands, meta-commands, scripting
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- **[postgresql-performance.md](references/postgresql-performance.md)** - EXPLAIN, query optimization, vacuum, indexes
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- **[postgresql-administration.md](references/postgresql-administration.md)** - User management, backups, replication, maintenance
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## Python Utilities
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Database utility scripts in `scripts/`:
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- **db_migrate.py** - Generate and apply migrations for both databases (MongoDB and PostgreSQL)
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- **db_backup.py** - Backup and restore MongoDB and PostgreSQL
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- **db_performance_check.py** - Analyze slow queries and recommend indexes
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```bash
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# Generate migration
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python scripts/db_migrate.py --db mongodb --generate "add_user_index"
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# Run backup
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python scripts/db_backup.py --db postgres --output /backups/
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# Check performance
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python scripts/db_performance_check.py --db mongodb --threshold 100ms
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```
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## Best Practices
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**MongoDB:**
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- Use embedded documents for 1-to-few relationships
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- Reference documents for 1-to-many or many-to-many
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- Index frequently queried fields
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- Use aggregation pipeline for complex transformations
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- Enable authentication and TLS in production
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- Use Atlas for managed hosting
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**PostgreSQL:**
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- Normalize schema to 3NF, denormalize for performance
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- Use foreign keys for referential integrity
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- Index foreign keys and frequently filtered columns
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- Use EXPLAIN ANALYZE to optimize queries
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- Regular VACUUM and ANALYZE maintenance
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- Connection pooling (pgBouncer) for web apps
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## Resources
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- MongoDB: https://www.mongodb.com/docs/
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- PostgreSQL: https://www.postgresql.org/docs/
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- MongoDB University: https://learn.mongodb.com/
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- PostgreSQL Tutorial: https://www.postgresqltutorial.com/
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