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Why This Tool?

The PostgreSQL community has explain.dalibo.com and PEV2. MySQL had nothing comparable — until now.

MySQL's raw EXPLAIN output tells you everything about query performance, but reading nested tree output or JSON plans isn't intuitive. This tool does the reading for you: paste your EXPLAIN output, get a visual tree with automatic issue detection, smart index recommendations, and executable query rewrites.

100% client-side — your query plans never leave your browser. No backend, no API calls, no account required.

Features

Analysis Engine

Feature	Details
Detection Rules	49 rules (8 critical, 20 warning, 5 info, 7 good, 4 MariaDB-specific, 5 MySQL 8.0+)
Index Advisor	Query-aware, resolves table aliases, suggests composite covering indexes, PK-aware
Query Rewrites	7 patterns: YEAR()→range, subquery→JOIN, NOT IN→LEFT JOIN, OFFSET→keyset, and more
Impact Simulator	Predicts structural plan changes per index (access type, row reduction, covering scan)
Scoring	Weighted 0-100 score with severity breakdown

Visualization

• Interactive tree — edge thickness = row count, color-coded node badges (Slow/Costly/Bad Estimate/Filter)
• Highlight modes — switch between duration, rows, and cost heat maps
• 4 view tabs — Tree, Table, Cost Chart, Estimate vs Actual
• Before/After — compare two plans side by side

Supported Formats

Format	Engine	Example
EXPLAIN ANALYZE (tree)	MySQL 8.0+	-> Nested loop inner join (cost=7.45 rows=16) (actual time=0.08..0.16 rows=16 loops=1)
EXPLAIN FORMAT=JSON	MySQL / MariaDB	{ "query_block": { "select_id": 1, ... } }
Traditional table	MySQL / MariaDB	+----+------+-------+------+------+-------+
ANALYZE table	MariaDB 10.1+	Includes r_rows and r_filtered columns
ANALYZE FORMAT=JSON	MariaDB 10.1+	Includes r_total_time_ms, filesort nesting

Paste directly from your terminal — the tool auto-strips mysql> prompts, | ... | borders, +---+ separators, SQL continuation lines (-> SELECT, -> GROUP BY), and N rows in set footers.

Quick Start

Use the hosted version (recommended)

reliadb.com/tools/explain/ — zero setup, always up to date.

Run locally

git clone https://github.com/Mughees52/mysql-explain-analyzer.git
cd mysql-explain-analyzer
npm install
npm run dev       # Dev server at localhost:5173

Build for production

npm run build     # Output in dist/
npm run preview   # Preview the build

How to Use

1. Run EXPLAIN ANALYZE on your slow query:

   EXPLAIN ANALYZE SELECT * FROM orders WHERE status = 'pending';
   

2. Paste the output into the EXPLAIN Output box — paste it exactly as your terminal prints it, borders and all.

3. Add your SQL query (optional) in the "SQL Query" tab — unlocks query rewrite suggestions.

4. Add table DDL (optional) in the "Table Schema" tab — unlocks composite index recommendations and schema analysis.

What It Catches

Full table scan on `orders` (50,529 rows)
├── Critical: No index on WHERE columns
├── Recommendation: ALTER TABLE orders ADD INDEX idx_status (status);
└── Impact: Full table scan (ALL) → Index lookup (ref)

Filesort on 10,000 rows
├── Warning: ORDER BY not covered by index
├── Recommendation: ALTER TABLE orders ADD INDEX idx_status_amount (status, total_amount);
└── Impact: Eliminates filesort, reads in index order

Dependent subquery (executes once per outer row)
├── Critical: O(n*m) complexity
├── Rewrite: Convert to JOIN
└── Generated SQL provided

Detection Rules Summary

Severity	Count	Examples
Critical	8	Full table scan (large), filesort >1K rows, temp table, Cartesian join, dependent subquery, unindexed nested loop, massive row mismatch
Warning	20	Row estimate mismatch >10x, no index available, full index scan, high loop count, join buffer, backward scan
Info	5	Small table scan, ICP used, subquery materialized, hash join, covering index
Good	7	Optimal eq_ref, covering index, efficient range scan, PK lookup
MariaDB	4	Rowid filter, FirstMatch/LooseScan semi-join, hash join, low r_filtered
MySQL 8.0+	5	Hash join, parallel scan, skip scan, index merge, antijoin

Index Advisor Intelligence

Not a simple "column in WHERE → add index" tool. The advisor:

• Merges cross-clause columns — WHERE + JOIN + GROUP BY + ORDER BY + aggregates combined into one optimal composite index
• PK-aware — never suggests indexes starting with primary key columns
• DDL-validated — confirms recommended columns actually exist in the table schema
• Deduplicates — removes subset indexes in favor of wider covering indexes
• Existing index aware — skips recommendations that duplicate existing indexes

Sharing & Embedding

• Share Link — generates a URL with the plan compressed in the hash. Anyone with the link sees your analysis.
• Embed — generates an <iframe> snippet for blog posts, runbooks, or internal docs.

Tech Stack

Technology	Purpose
Vue 3	UI framework
TypeScript	Type-safe analysis engine
Vite	Build tool
Tailwind CSS	Styling
D3.js	Tree visualization
CodeMirror 6	SQL input editor
Pako	URL compression for sharing

Testing

Tested against 50 real queries on a 680K-row MySQL 8.0.45 database (100K orders, 50K users, 250K order items, 80K reviews) and a 530K-row MariaDB 10.11.14 database.

# Set up test database
mysql -u root < tests/setup-test-db.sql

# Run analysis tests (50 queries)
npx tsx tests/run-tests.ts

Test Results

Metric	Result
Queries tested	50
Issues detected	102
Index recommendations	42
Impact simulations	23
Query hints	40
Query rewrites	8
Average score	86/100
Errors	0

Compared against independent senior DBA analysis — matches on 90% of findings. Full comparison in tests/ai-comparison.md.

Contributing

Issues and pull requests are welcome. Please open an issue first to discuss what you'd like to change.

Related

• explain.dalibo.com — PostgreSQL EXPLAIN visualizer
• PEV2 — PostgreSQL EXPLAIN visualizer (Vue)
• awesome-mysql — Curated MySQL tools list

Built By

ReliaDB — PostgreSQL & MySQL DBA consulting for growing SaaS and tech companies.

Based in Valencia, Spain. Supporting teams globally.

License

MIT