Indexer Node

The node continuously listens to the blockchain network, ingesting raw data from blocks and transactions. It parses this data according to predefined schemas, extracting and decoding relevant information such as:

• Smart contract events and their parameters
• Transaction details (sender, receiver, value)
• Block metadata (timestamp, miner, gas used)
• Internal message calls and state changes

Indexing logic is deterministic, meaning the same input data will always produce the same indexed output. This is critical for decentralization, as it allows multiple independent nodes to verify each other's work and achieve consensus on the indexed state, ensuring data integrity and reliability.

The node exposes the indexed data through a query interface, typically a GraphQL API. This allows decentralized applications (dApps) to request specific, aggregated data (e.g., "all NFT transfers for this wallet in the last week") without needing to process raw blockchain data themselves, drastically improving performance and developer experience.

To serve queries efficiently, the node maintains an optimized database (often PostgreSQL) of the indexed state. It implements advanced caching strategies for frequent queries and manages historical data, enabling fast access to both real-time and historical blockchain information.

In networks like The Graph, indexer nodes participate in a decentralized marketplace. They stake the network's native token, publish their services, and are rewarded for accurately serving queries. They can be slashed for malicious behavior, aligning economic incentives with honest service.

A core function is executing subgraphs—open-source mapping instructions that define what data to index from the blockchain and how to transform it. The node runs these mappings, which are written in AssemblyScript or other languages, to populate its database with application-specific data.

The primary function is to ingest raw blockchain data from a full node or RPC endpoint. It then processes and transforms this data into a structured, queryable format (like a relational database) by applying predefined logic or subgraph manifests. This involves filtering events, decoding logs, and establishing relationships between entities.

Indexers expose a GraphQL API, providing a single, powerful endpoint for applications to query. Unlike direct RPC calls, this allows for complex, nested queries (e.g., "get all NFT transfers for this user, including collection details") in a single request, dramatically improving developer experience and application performance.

In networks like The Graph, indexer nodes operate in a decentralized marketplace. They:

• Stake the network's native token (GRT) as collateral.
• Earn query fees and indexing rewards for serving data.
• Can be slashed for malicious behavior or downtime. This creates an economic model for reliable, uncensorable data access.

Indexers host and execute specific subgraphs—open APIs that define what data to index and how to transform it. Developers publish subgraphs, and indexers choose which ones to index based on demand and economic incentives. The indexer syncs to the chain head, continuously updating the subgraph's data store.

For performance, indexers implement sophisticated query planning, execution, and caching layers. They parse incoming GraphQL queries, optimize them against the underlying data store (often PostgreSQL), and cache frequent query results. This ensures low-latency responses (often <100ms) for dApp users, which is critical for user experience.

Key differentiators from a standard node:

• Purpose: Full nodes validate/relay transactions; indexers organize historical data for queries.
• Data Structure: RPCs offer low-level, chain-state access. Indexers provide high-level, application-shaped data.
• Query Language: RPCs use custom methods (eth_getLogs). Indexers use declarative GraphQL.
• Performance: Indexers are optimized for complex historical queries, not real-time transaction propagation.

Indexers must stake the network's native token (e.g., GRT, AXL) as collateral. This stake is subject to slashing for malicious behavior or downtime, aligning economic incentives with honest service provision. The stake also determines query allocation and potential rewards.

Indexers earn revenue by charging micro-payments for each query they serve. Fees are set by the indexer and paid in the protocol's token. A competitive marketplace forms where delegators may stake with indexers based on their fee structure, performance, and reliability.

To prevent serving incorrect data, indexers may be required to provide cryptographic proofs of indexing or participate in dispute resolution mechanisms. Fraudulent proofs can result in slashed stakes. This creates a cryptoeconomic guarantee for data correctness.

Running an indexer requires robust, high-uptime infrastructure. Key considerations include:

• DDoS Protection: To maintain service availability.
• Private Key Management: Securing the wallet holding the staked assets.
• Database Security: Protecting the indexed data from tampering or leaks.

Delegators are token holders who stake with an indexer without running infrastructure, sharing in its rewards and risks. This relationship introduces a principal-agent problem. Indexers must maintain performance to retain delegators, whose stake can be withdrawn (after an unbonding period) if they lose confidence.

Indexers are exposed to systemic risks within the indexing protocol itself, including:

• Smart Contract Risk: Bugs in the staking, rewards, or slashing contracts.
• Governance Risk: Protocol upgrades that alter economic parameters.
• Token Volatility: Fluctuations in the value of staked and earned tokens.

A platform where indexers can stake tokens and offer their query services for sale. Consumers (dApps) pay for queries using a network token. This creates a cryptoeconomic marketplace for reliable data, aligning incentives for indexer performance and uptime. The Graph Network is a primary example.

A query is a request for specific indexed data, typically using a language like GraphQL. Instead of scanning the blockchain, dApps send queries to an indexer's API endpoint. The indexer executes this against its optimized database, returning results like token balances, transaction histories, or aggregated statistics in milliseconds.

A state channel is a Layer 2 scaling technique where transactions are executed off-chain, with only the final state settled on-chain. Indexers face the challenge of tracking both on-chain settlement transactions and the off-chain state updates, requiring specialized logic to provide a complete data view for applications using channels.