How Portal serves data - SQD Documentation

Portal can read different parts of one requested block range from two source types:

Archival data supplies finalized history. It can lag the chain head, meaning the latest available block, by several hours.
Recent data can supply blocks closer to the chain head. These blocks may not be finalized and can be replaced after a chain reorganization.

Portal selects the source for each part of the range. The client uses the same dataset URL when the source changes. For example, this endpoint can return historical blocks first and recent blocks when the request reaches the chain head:

POST /datasets/ethereum-mainnet/stream

Changing sources does not change the JSON Lines response format. The source can affect which blocks are currently available and whether a response includes blocks near the chain head. To choose between standard and finalized streams, see Finalized and recent data. For the request loop used to read a range, see EVM stream continuation or Solana stream continuation.