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mysql

Plan and review MySQL/InnoDB schema, indexing, query tuning, transactions, and operations. Use when creating or modifying MySQL tables, indexes, or queries; diagnosing slow/locking behavior; planning migrations; or troubleshooting replication and connection issues. Load when using a MySQL database.

Install with Tessl CLI

npx tessl i github:planetscale/database-skills --skill mysql
What are skills?

Overall
score

93%

Does it follow best practices?

Evaluation94%

1.04x

Agent success when using this skill

Validation for skill structure

SKILL.md
Review
Evals

Evaluation results

98%

25%

Design a MySQL Schema for a Multi-Tenant SaaS Order Management System

Schema design and data type selection

Criteria
Without context
With context

BIGINT UNSIGNED AUTO_INCREMENT PK

0%

80%

UUID in secondary column

100%

100%

UUID stored as BINARY(16)

100%

100%

utf8mb4 character set

100%

100%

utf8mb4_0900_ai_ci collation

0%

100%

DATETIME not TIMESTAMP

100%

100%

NOT NULL preference

100%

100%

Lookup tables over ENUM

25%

100%

DECIMAL for money

100%

100%

Appropriate VARCHAR sizing

100%

100%

3NF normalization

100%

100%

89%

-7%

Optimize Slow Queries for an E-Commerce Analytics Dashboard

Composite index design and query optimization

Criteria
Without context
With context

Equality before range in composite index

100%

100%

Range stops subsequent index usage

100%

63%

Remove function on indexed column

100%

100%

Cursor pagination for Query C

100%

100%

No SELECT * in rewritten queries

100%

0%

UNION ALL for Query D

60%

100%

EXPLAIN red flag identification

100%

100%

Composite index for tenant + status queries

100%

100%

Index for GROUP BY optimization

100%

100%

Separate indexes or UNION for OR across columns

100%

100%

DESC in index or ORDER BY awareness

100%

100%

93%

10%

Design a Robust Inventory Reservation System with MySQL Transactions

Transaction isolation and deadlock handling

Criteria
Without context
With context

Consistent row access order

100%

100%

Error 1213 retry with backoff

100%

100%

I/O outside transaction

100%

100%

REPEATABLE READ as default

60%

80%

FOR UPDATE used sparingly

50%

90%

Short transaction duration

100%

100%

Backoff uses exponential delay

100%

100%

Max retry limit

100%

100%

Idempotency consideration

67%

83%

No global isolation change

100%

100%

Indexed WHERE columns

25%

63%

92%

-8%

Design a Partitioned Event Logging Table with Automated Retention

Time-series partitioning and data retention

Criteria
Without context
With context

RANGE partitioning used

100%

100%

Partition column in PRIMARY KEY

100%

100%

Partition column in UNIQUE KEY

100%

20%

MAXVALUE catch-all partition

100%

100%

DROP PARTITION for retention

100%

100%

REORGANIZE for new partitions

100%

100%

Monthly partition boundaries

100%

100%

BIGINT UNSIGNED AUTO_INCREMENT PK

100%

100%

No foreign keys on partitioned table

100%

100%

DATETIME not TIMESTAMP for recorded_at

100%

100%

Composite index for device lookups

100%

100%

100%

4%

Plan a Production Schema Migration and Data Backfill for a High-Traffic MySQL Database

Online DDL migration and bulk data operations

Criteria
Without context
With context

INSTANT for adding column

100%

100%

INPLACE for adding index

100%

100%

Explicit ALGORITHM specification

100%

100%

Column type change risks identified

100%

100%

External tool for large table rebuild

100%

100%

Batch update sizing

60%

100%

Connection pool formula

100%

100%

LOCK=NONE specified

100%

100%

Rollback steps included

100%

100%

Backfill uses batched WHERE with range or LIMIT

100%

100%

Replica testing recommended

100%

100%

Evaluated
Agent
Claude Code

Table of Contents

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