Analyze query performance with EXPLAIN plan interpretation, bottleneck identification, and optimization recommendations

MIT License

Free Pricing

Installation

Open Claude Code and run this command:

/plugin install query-performance-analyzer@claude-code-plugins-plus

Use --global to install for all projects, or --project for current project only.

What It Does

Analyze query performance with EXPLAIN plan interpretation and optimization recommendations.

Features

EXPLAIN Plan Analysis: Interpret execution plans
Bottleneck Detection: Identify performance issues
Index Recommendations: Suggest optimal indexes
Metrics Interpretation: Understand performance metrics
Cost Estimation: Predict query performance

Skills (1)

analyzing-query-performance SKILL.md View full skill →

Execute use when you need to work with query optimization.

ReadWriteEditGrepGlobBash(psql:*)Bash(mysql:*)Bash(mongosh:*)

Query Performance Analyzer

Overview

Analyze slow database queries using execution plans, wait statistics, and I/O metrics across PostgreSQL, MySQL, and MongoDB. This skill captures EXPLAIN output, identifies sequential scans on large tables, detects missing indexes, measures buffer cache hit ratios, and produces actionable optimization recommendations ranked by expected performance impact.

Prerequisites

Database credentials with permissions to run EXPLAIN ANALYZE (PostgreSQL), EXPLAIN FORMAT=JSON (MySQL), or explain() (MongoDB)
pgstatstatements extension enabled for PostgreSQL (provides aggregated query statistics)
Access to slow query logs or performance_schema (MySQL)
Baseline query execution times for comparison
psql, mysql, or mongosh CLI tools installed

Instructions

Identify the slowest queries by examining pgstatstatements (PostgreSQL): SELECT query, calls, meanexectime, totalexectime FROM pgstatstatements ORDER BY meanexectime DESC LIMIT 20. For MySQL, enable and query the slow query log or performanceschema.eventsstatementssummaryby_digest.

Run EXPLAIN (ANALYZE, BUFFERS, FORMAT JSON) on each slow query in PostgreSQL, or EXPLAIN ANALYZE FORMAT=JSON in MySQL. Capture the full execution plan including actual row counts, loop iterations, and buffer usage.

Analyze the execution plan for these red flags:

Sequential scans on tables with >10,000 rows (indicates missing index)
Nested loop joins with high outer row counts (consider hash join or merge join)
Sort operations without index support (adding a covering index eliminates the sort)
High rowsremovedby_filter relative to rows (predicate not selective enough)
Bitmap heap scans with high recheck rate (index selectivity too low)

Check buffer cache performance: SELECT heapblksread, heapblkshit, heapblkshit::float / (heapblkshit + heapblksread) AS cachehitratio FROM pgstatiousertables WHERE relname = 'tablename'. A ratio below 0.95 suggests the working set exceeds available shared_buffers.

Evaluate index usage with SELECT indexrelname, idxscan, idxtupread, idxtupfetch FROM pgstatuserindexes WHERE schemaname = 'public' ORDER BY idx_scan ASC. Indexes with zero scans are unused and waste write performance.

Check for table bloat using SELECT relname, nlive



      
      
          How It Works
          The performance agent activates when discussing query performance, EXPLAIN plans, or optimization.
        

      
      
          Use Cases
          Paste your EXPLAIN output or slow query, and receive detailed analysis with specific optimization recommendations.
        

      
      

      
      
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          Tags
          
            performancequeryoptimizationexplaindatabase