database-sharding

SKILL.md

Database Sharding

Table of Contents

Overview

When to Use

Quick Start

Reference Guides

Best Practices

Overview

Implement horizontal data partitioning across multiple database servers. Covers sharding strategies, consistent hashing, shard key selection, and cross-shard querying patterns.

When to Use

Database size exceeds single server capacity

Read/write throughput needs horizontal scaling

Geographic data distribution requirements

Multi-tenant data isolation

Cost optimization through distributed architecture

Load balancing across database instances

Quick Start

Minimal working example:

-- Define shard ranges
-- Shard 0: user_id 0-999999
-- Shard 1: user_id 1000000-1999999
-- Shard 2: user_id 2000000-2999999

CREATE TABLE users_shard_0 (
  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  user_id BIGINT NOT NULL,
  email VARCHAR(255) NOT NULL,
  created_at TIMESTAMP DEFAULT NOW(),
  CONSTRAINT shard_0_range CHECK (user_id BETWEEN 0 AND 999999)
);

CREATE TABLE users_shard_1 (
  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  user_id BIGINT NOT NULL,
  email VARCHAR(255) NOT NULL,
  created_at TIMESTAMP DEFAULT NOW(),
  CONSTRAINT shard_1_range CHECK (user_id BETWEEN 1000000 AND 1999999)
);

-- Function to determine shard
CREATE OR REPLACE FUNCTION get_shard_id(p_user_id BIGINT)
RETURNS INT AS $$
BEGIN
// ... (see reference guides for full implementation)

Reference Guides

Detailed implementations in the references/ directory:

Guide
Contents

Range-Based Sharding
Range-Based Sharding

Hash-Based Sharding
Hash-Based Sharding

Directory-Based Sharding
Directory-Based Sharding

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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