> ## Documentation Index
> Fetch the complete documentation index at: https://docs.qu.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Sharding

> How sharding is implemented and used to scale in Quai Network.

## Making Blockchains Work Like Modern Databases

Traditional databases solved the scaling problem decades ago through sharding - splitting data across multiple servers. Quai brings this proven approach to blockchain, but with a crucial innovation: maintaining full security across all shards.

## What is Sharding?

**Database Sharding (Traditional):**
Imagine a library that gets too big for one building:

* **Solution**: Split books across multiple buildings (shards)
* **Benefit**: More librarians can help visitors simultaneously
* **Challenge**: Need a system to know which building has which book

**Blockchain Sharding:**
The same concept, but for decentralized networks:

* **Traditional approach**: Split both data AND security (dangerous)
* **Quai's approach**: Split only data, keep security unified (safe)

## How Quai Implements Sharding

**Key Benefits:**

1. **Parallel Processing**
   * Each shard processes transactions independently
   * Like having multiple checkout lines instead of one
   * Result: 50,000+ TPS capacity

2. **Lower Node Requirements**
   * Nodes can choose to track only specific shards
   * Reduces hardware requirements for participation
   * More accessible = more decentralized

3. **Geographic Optimization**
   * Shards naturally organize by region
   * Minimizes latency within each shard
   * Better performance worldwide

## Smart Address System

**The Problem:** How do you know which shard handles which transaction?

**Quai's Solution:** Addresses contain built-in routing information - like ZIP codes for blockchain.

**How It Works:**
Every Quai address has a 9-bit prefix that acts like a postal code:

* **First 4 bits**: Region identifier (like country)
* **Next 4 bits**: Zone within region (like city)
* **Last bit**: Currency type (Quai or Qi)

#### Formatting

The table below specifies the format for each bit in the shard identifier.

| bits 0-3      | bits 4-7    | bit 8             |
| ------------- | ----------- | ----------------- |
| region number | zone number | ledger identifier |

### Simple Examples

| Example Address (shortened) | Location          | Currency |
| --------------------------- | ----------------- | -------- |
| 0x000...                    | Region 0, Zone 0  | Quai     |
| 0x2A4...                    | Region 2, Zone 10 | Quai     |
| 0x008...                    | Region 0, Zone 0  | Qi       |

**Benefits:**

* **Instant routing**: Nodes immediately know where to send transactions
* **No lookups needed**: Address itself contains all routing info
* **Efficient processing**: Eliminates cross-shard confusion

For technical details, see [QIP-2](https://github.com/quai-network/qips/blob/master/qip-0002.md).

## The Security Breakthrough

**Traditional Sharding's Fatal Flaw:**

* 10 shards = each gets 1/10th of security
* Attackers can focus on the weakest shard
* Like having 10 weak locks instead of one strong lock

**Quai's Innovation:**
Through [coincident blocks](/learn/advanced-introduction/merged-mining/coincident-blocks) and merged mining:

* Every shard maintains 100% network security
* Attacking one shard requires attacking the entire network
* Like having the same unbreakable lock protecting every door

**How It Works:**

1. **Hierarchical structure** organizes all shards
2. **Hash linked references** connect every chain
3. **Atomic operations** ensure all shards advance together
4. **Result**: Unlimited shards, uncompromised security

## Legacy Testnet Mappings

Early testnets use a lighter 9-shard hierarchy. It has already been concluded that the mainnet should accommodate more than 9 shards, so this mapping is no longer recommended. We make note of it here for wallet compatibility with early testnets.

To find the address shard specification in detail please visit [QIP-4](https://github.com/quai-network/qips/blob/master/qip-0004.md).