database-performance-debugging
Debug database performance issues through query analysis, index optimization, and execution plan review. Identify and fix slow queries.
What this skill does
# Database Performance Debugging ## Table of Contents - [Overview](#overview) - [When to Use](#when-to-use) - [Quick Start](#quick-start) - [Reference Guides](#reference-guides) - [Best Practices](#best-practices) ## Overview Database performance issues directly impact application responsiveness. Debugging focuses on identifying slow queries and optimizing execution plans. ## When to Use - Slow application response times - High database CPU - Slow queries identified - Performance regression - Under load stress ## Quick Start Minimal working example: ```sql -- Enable slow query log (MySQL) SET GLOBAL slow_query_log = 'ON'; SET GLOBAL long_query_time = 0.5; -- View slow queries SHOW GLOBAL STATUS LIKE 'Slow_queries'; SELECT * FROM mysql.slow_log; -- PostgreSQL slow queries CREATE EXTENSION pg_stat_statements; SELECT mean_exec_time, calls, query FROM pg_stat_statements ORDER BY mean_exec_time DESC LIMIT 10; -- SQL Server slow queries SELECT TOP 10 execution_count, total_elapsed_time, statement_text FROM sys.dm_exec_query_stats ORDER BY total_elapsed_time DESC; -- Query profiling EXPLAIN ANALYZE SELECT * FROM orders WHERE user_id = 123; // ... (see reference guides for full implementation) ``` ## Reference Guides Detailed implementations in the `references/` directory: | Guide | Contents | |---|---| | [Identify Slow Queries](references/identify-slow-queries.md) | Identify Slow Queries | | [Common Issues & Solutions](references/common-issues-solutions.md) | Common Issues & Solutions | | [Execution Plan Analysis](references/execution-plan-analysis.md) | Execution Plan Analysis | | [Debugging Process](references/debugging-process.md) | Debugging Process | ## Best Practices ### ✅ DO - Follow established patterns and conventions - Write clean, maintainable code - Add appropriate documentation - Test thoroughly before deploying ### ❌ DON'T - Skip testing or validation - Ignore error handling - Hard-code configuration values
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