SQD Network components - SQD Documentation

SQD Network is a set of services with different responsibilities. Finalized blockchain data is written to chunk storage and copied to worker disks. Recent chain-tip data follows a separate path through HotblocksDB. Portal chooses one of these sources for each request. Smart contracts record participation and token accounting, but they do not carry block data or query results.

Data services

Component	Responsibility
Archive ingestion	Reads finalized blocks from configured sources, validates their order, and writes chunk files to persistent storage.
Persistent chunk storage	Holds the source copy of archival chunks from which workers download their assignments. The current implementation uses S3-compatible object storage.
Workers	Keep assigned chunks on local disk and execute queries against those chunks.
Chain-specific data service	Reads a chain source and exposes blocks, fork signals, and finality signals to HotblocksDB. The current EVM service reads an RPC endpoint; other chain families require a compatible service.
HotblocksDB	Maintains a bounded, contiguous, fork-aware window near each configured dataset’s head and executes range queries over that window. It is not an archival store.
Hotblocks-retain	Reads the last indexed archival height from scheduler status and, after the assignment becomes effective plus a configured delay, updates the HotblocksDB retention lower bound. It does not copy block data.
Portal	Accepts HTTP requests. It sends archival requests to assigned workers and forwards recent requests to HotblocksDB, then streams the selected source’s response to the client.

Coordination services

Component	Responsibility
Scheduler	Reads the known chunks and worker set, calculates which workers should hold each chunk, and publishes an assignment.
Assignment publisher	Makes the current network state and compressed assignment available to workers and Portal.
Peer-to-peer transport	Carries worker queries, results, heartbeats, and logs over libp2p and QUIC.
Bootnodes	Help a node find peers when it first joins the peer-to-peer network.
Observers and collectors	Record peer reachability, worker status, heartbeats, and query logs for operators.
Smart contracts	Record worker registration, bonds, delegation, network parameters, allocations, and rewards on Arbitrum.

Portal does not combine worker and HotblocksDB records in one response. The request’s first block determines the source, and a later client request can cross the boundary. See How real-time data is served.

Continue through the architecture

From blocks to chunks

Follow finalized blocks into storage and onto worker disks.

Scheduling and replication

See how the current scheduler builds a worker assignment.

How a query is served

Follow an archival request from Portal to a worker and back.

How real-time data is served

Follow recent blocks through HotblocksDB and Portal.

Onchain and offchain

See which records are onchain and which work happens offchain.

Implementation sources

This page is based on the current public implementations:

​Data services

​Coordination services

​Continue through the architecture