Explore the code Blocks pushed as produced
No loop, no polling budget.
Real-time streams
Get the block.
Stop asking for it.
A continuous stream rather than a polling loop, with a cursor to resume from and reorganizations stated explicitly.
- Push, not poll
- Cursor and resume
- Explicit reorgs
- Same path as history
Ethereum → Firehose → Substreams → PostgreSQL
Interactive illustration
StreamingFast
ecosystem
01 Real-time streams
Looks familiar?
Most of your requests return the block you already had, and you paid for all of them.
A poll was missed. Nothing errored. The range is simply not there.
History and live disagree about a balance, because they are two different code paths.
Want to watch your own chain arrive?
Get an API key
RUST → WEBASSEMBLYPush beats poll, and it is not close.
Polling pays for the question, not the answer, and a missed poll looks exactly like silence. A pushed stream delivers the block when it exists, carries a cursor you persist, and signals a reorganization instead of quietly rewriting history underneath you. And it is the same path your backfill used, so the two cannot drift.
Read the guideFilterMapAggregateDeliver
▧ substreams.yamlPACKAGE STRUCTURE
01 specVersion: v0.1.0
02 package:
03 name: token_transfers
04 version: v0.1.0
05
06 modules:
07 - name: map_transfers
08 kind: map
09 inputs:
10 - source: sf.ethereum.type.v2.Block
11 output:
12 type: proto:transfers.Transfers Illustrative excerpt Build a complete package ↗
What you get
A cursor
Reconnect where you stopped, not at the head.
Explicit reorganizations
A signal you can act on, not a number that changed.
Decoded at the head
The same entities you get from history.
One implementation
History and live share the path, so they cannot disagree.
02 Real-time streams
How it works
FROM HISTORY TO THE CHAIN HEAD
Historical blocksNew blocks
TRANSACTIONS
TRACES & LOGS
STATE CHANGES
Rich block data. One continuous stream.
Open the stream
Blocks arrive with their decoded content.
Hold the cursor
Persist it. That is the whole recovery story.
Handle the undo
Reorganizations are explicit, so your database can follow.
Want to watch your own chain arrive?
Get an API key03 Real-time streams
What you stop owning
[01]
A polling loop and its quota
[02]
The gap detection nobody built
[03]
A second code path for live data
Real-time streams
Stream your chain, not a sample.
Read the guide ↗Build a reliable blockchain-to-SQL pipeline
Choose the mapping, preserve progress and operate ingestion with clear freshness and cost expectations.