database-sharding

Database sharding for PostgreSQL/MySQL with hash/range/directory strategies. Use for horizontal scaling, multi-tenant isolation, billions of records, or encountering wrong shard keys, hotspots, cross-shard transactions, rebalancing issues.

Install with Tessl CLI

npx tessl i github:secondsky/claude-skills --skill database-sharding

What are skills?

Review — 92%

Does it follow best practices?

Evaluation — 92%

Agent success when using this skill

Validation — 10 / 11 Passed

Validation for skill structure

SKILL.md

Review

Evals

Evaluation results

92%

13%

Scalable Shard Router for User Data

Consistent hashing router implementation

Criteria

Without context

With context

No simple modulo

100%

Consistent hash ring

100%

Virtual node count

100%

MD5 or strong hash

100%

Connection pool per shard

Router abstraction layer

100%

4-shard example

100%

Single-shard query method

100%

All-shards query method

100%

addNode support

50%

100%

Wrap-around logic

100%

Without context: $0.2739 · 1m 13s · 10 turns · 11 in / 4,849 out tokens

With context: $0.6270 · 1m 44s · 18 turns · 17 in / 6,163 out tokens

90%

15%

Analytics Query Utilities for a Sharded Orders Database

Cross-shard aggregation with SQL injection prevention

Criteria

Without context

With context

Parallel scatter-gather

100%

validateIdentifier function

33%

100%

quoteIdentifier function

100%

table validated in countAcrossShards

100%

column validated in sumAcrossShards

100%

groupKey validated in groupByAcrossShards

12%

100%

COUNT merge correct

100%

SUM/AVG merge correct

100%

GROUP BY merge correct

100%

Security docs in README

100%

Error handling on shard failure

Without context: $0.2212 · 57s · 10 turns · 10 in / 3,502 out tokens

With context: $0.4325 · 1m 19s · 16 turns · 15 in / 4,411 out tokens

94%

14%

Shard Key Selection and Monitoring Strategy for a Project Management SaaS

Shard key selection and monitoring design

Criteria

Without context

With context

Rejects 'status' key

100%

Cardinality threshold cited

20%

100%

5% distribution rule

80%

100%

Immutability criterion

100%

Query alignment criterion

75%

100%

Rejects timestamp key

100%

Initial shard count range

100%

Storage alert threshold

100%

75%

Load imbalance threshold

75%

validate-distribution.sql cardinality check

100%

validate-distribution.sql frequency check

100%

Production data caveat

66%

Without context: $0.3982 · 2m 18s · 11 turns · 12 in / 7,945 out tokens

With context: $0.6849 · 2m 58s · 16 turns · 15 in / 10,160 out tokens

Evaluated: about 6 hours ago
Agent: Claude Code

Table of Contents

Scalable Shard Router for User Data Analytics Query Utilities for a Sharded Orders Database Shard Key Selection and Monitoring Strategy for a Project Management SaaS

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