Common Questions

Blockchain data questions, answered directly

Direct answers to the questions developers actually ask about blockchain data — indexing, pipelines, and building indexers with AI assistants.

Foundations

What is blockchain indexing?How do blockchain indexers work?What is Substreams?What is a blockchain Firehose?What's the difference between Firehose and Substreams?What is blockchain ETL?What is a flat-file blockchain dataset?

Choosing an approach

RPC vs indexing — what's the difference?Polling vs streaming blockchain data — which should you use?Subgraph vs API — which should you use?Do I need an archive node to get historical data?Can I get full history and real-time data from one source?Do I need to run a node to index blockchain data?

Building with AI

Can I build a Substreams package without knowing Rust?How do I build a blockchain indexer with an AI coding assistant?What are the Substreams agent skills?

Pipelines and databases

How do I stream onchain data to a database?What are Hosted Sinks?How do I backfill historical blockchain data?

AI agents and onchain data

How do AI agents access onchain data?Can an LLM query blockchain data directly?

Troubleshooting

Why is my subgraph syncing so slow?What is a blockchain reorg, and how do indexers handle it?