# Indexing and Querying Data

### **Introduction**

Studio Blockchain’s advanced indexing and querying system ensures developers have seamless access to blockchain data for dApp development, analytics, and transaction monitoring. Leveraging a PostgreSQL-backed indexer and comprehensive REST APIs, Studio Blockchain provides real-time and historical data with robust performance enhancements. This guide walks you through the capabilities of the indexer and how to query data effectively.

***

### **1. Key Features of the Studio Blockchain Indexer**

1. **Dual Connection System:**
   * Supports both HTTP and WebSocket connections for data access.
   * Real-time block processing ensures minimal latency.
2. **Optimized Data Storage:**
   * Uses PostgreSQL for efficient storage and retrieval of blockchain data.
   * Provides advanced features like pagination and filtering.
3. **Comprehensive REST API:**
   * Endpoints to access blocks, transactions, contracts, and addresses.
   * Historical and real-time data available.
4. **Scalability and Performance:**
   * AI-enhanced query optimization ensures fast response times.
   * Designed to handle high transaction throughput without bottlenecks.

***

### **2. Setting Up the Indexer**

The Studio Blockchain indexer requires PostgreSQL as a backend. Follow these steps to set it up:

#### **Step 1: Install PostgreSQL**

1. Install PostgreSQL on your machine:

   ```bash
   bashCopy codesudo apt update
   sudo apt install postgresql postgresql-contrib
   ```
2. Start the PostgreSQL service:

   ```bash
   bashCopy codesudo service postgresql start
   ```

#### **Step 2: Configure the Database**

1. Create a new PostgreSQL user and database:

   ```bash
   bashCopy codesudo -u postgres createuser studio-indexer
   sudo -u postgres createdb studio-db --owner=studio-indexer
   ```
2. Set a password for the `studio-indexer` user:

   ```bash
   bashCopy codesudo -u postgres psql
   ALTER USER "studio-indexer" WITH PASSWORD 'yourpassword';
   \q
   ```

#### **Step 3: Run the Indexer**

Clone the Studio Blockchain repository if not done already:

```bash
bashCopy codegit clone https://github.com/studio-blockchain/studio-blockchain.git
cd studio-blockchain
```

Run the indexer:

```bash
bashCopy code./build/bin/studio-indexer --config=config/indexer-config.yaml
```

Ensure the configuration file (`indexer-config.yaml`) is correctly set up with your database credentials and network RPC.

***

### **3. REST API Endpoints**

Studio Blockchain’s REST API provides developers with extensive capabilities for querying blockchain data. Below are the key endpoints:

#### **Block Data**

* **Get Latest Block:**

  ```bash
  bashCopy codeGET /blocks/latest
  ```

  Example Response:

  ```json
  jsonCopy code{
    "number": 123456,
    "hash": "0xabc123...",
    "timestamp": "2024-01-01T12:34:56Z",
    "transactions": 30,
    "miner": "0xValidatorAddress"
  }
  ```
* **Get Block by Number:**

  ```bash
  bashCopy codeGET /blocks/:number
  ```

  Replace `:number` with the block number (e.g., `/blocks/100`).

***

#### **Transaction Data**

* **Get Latest Transactions:**

  ```bash
  bashCopy codeGET /transactions/latest
  ```

  Example Response:

  ```json
  jsonCopy code[
    {
      "hash": "0xtransaction123...",
      "from": "0xSenderAddress",
      "to": "0xRecipientAddress",
      "value": "1000000000000000000",
      "gasUsed": 21000
    }
  ]
  ```
* **Get Transaction by Hash:**

  ```bash
  bashCopy codeGET /transactions/:hash
  ```

  Replace `:hash` with the transaction hash.

***

#### **Address Activity**

* **Get Transactions for an Address:**

  ```bash
  bashCopy codeGET /address/:address/transactions
  ```

  Replace `:address` with the wallet address.

***

#### **Contract Verification**

* **Submit Contract for Verification:**

  ```bash
  bashCopy codePOST /v2/contract/verify
  ```

  Example Payload:

  ```json
  jsonCopy code{
    "address": "0xContractAddress",
    "sourceCode": "pragma solidity ^0.8.0; contract MyContract { ... }",
    "compilerVersion": "0.8.19",
    "evmVersion": "PARIS",
    "constructorArgs": "..."
  }
  ```

***

#### **Health Check**

* **Check Indexer Health:**

  ```bash
  bashCopy codeGET /health
  ```

  Example Response:

  ```json
  jsonCopy code{
    "status": "healthy",
    "lastIndexedBlock": 123456,
    "connectedPeers": 10
  }
  ```

***

### **4. WebSocket for Real-Time Updates**

Studio Blockchain’s WebSocket endpoint provides developers with real-time data feeds.

#### **Subscription Example:**

```javascript
javascriptCopy codeconst WebSocket = require('ws');
const ws = new WebSocket('wss://ws.studio-blockchain.com');

ws.on('open', function open() {
    ws.send(JSON.stringify({
        jsonrpc: '2.0',
        method: 'eth_subscribe',
        params: ['newBlockHeaders'],
        id: 1
    }));
});

ws.on('message', function message(data) {
    console.log('New Block:', data);
});
```

***

### **5. Querying Gas Usage Metrics**

Access block-level gas metrics via the API:

* **Get Gas Usage Statistics:**

  ```bash
  bashCopy codeGET /blocks/:number/gas
  ```

  Example Response:

  ```json
  jsonCopy code{
    "gasUsed": 12000000,
    "gasLimit": 15000000,
    "baseFeePerGas": "20000000000"
  }
  ```

***

### **6. Best Practices**

1. **Efficient Querying:**
   * Use pagination for endpoints that return large datasets (e.g., `/blocks`).
   * Subscribe to WebSocket events for real-time updates instead of polling.
2. **Indexing Custom Data:**
   * Extend the indexer to store application-specific data (e.g., NFT metadata or custom token statistics).
3. **Monitoring Indexer Health:**
   * Regularly check the `/health` endpoint for service status and performance metrics.

***

### **Next Steps**

Now that you understand how to index and query data:

1. Proceed to explore **Ecosystem Development** for insights into Studio Blockchain’s broader dApp ecosystem.
2. Set up real-time data analytics pipelines using WebSocket subscriptions and the REST API.
3. Contribute to Studio Blockchain by extending the indexer or creating new tools for developers.