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Common questions about developing with Squid SDK.

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Real-World Applications

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What are some real-world applications for which Squid SDK was a good fit?

Squid SDK is well-suited for a wide range of blockchain indexing applications:
  • DeFi Backends - UIs and dashboards for a variety of dApps, including DEXs, NFT marketplaces etc.
  • Historical Price Feeds - Track Uniswap trades and Chainlink oracle contracts
  • Smart Contract Analysis - Mine contract deployments and analyze bytecode
  • Real-time Bots - Build bots with ~1-2 sec delay triggered by on-chain activity
Squid SDK excels at applications requiring high-performance indexing, complex data transformations, and real-time processing.

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Technical Questions

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My squid is slow, failing, or misbehaving — where do I start?

Start with the diagnostic sequence in Squid SDK tips and troubleshooting: it covers indexing speed, batch behavior, memory, reorgs, debug logging, and common error messages. Many production issues can also be prevented by following the SQD Cloud best practices guide.

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How does Squid SDK handle unfinalized blocks?

The Portal stream serves blocks all the way to the chain tip, including unfinalized ones. Run the source with a hot-block-aware database (TypeormDatabase({supportHotBlocks: true})) and chain reorganizations are rolled back automatically — handler code never sees forks. For detailed information, see Indexing unfinalized blocks.

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How do squids keep track of their sync progress?

Sync progress tracking depends on the data sink used: TypeORM Database: Processors using TypeormDatabase store their state in a PostgreSQL schema (not a table). By default, the schema is called squid_processor.
The schema name must be overridden in multiprocessor squids.
View sync status:
Reset processor status:
File-based datasets: Squids using file-based storage store their status in status.txt by default. This can be customized via the hooks database option.

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How fresh is the data served by squids?

The Portal stream serves unfinalized blocks in real time, so indexing latency is minimal out of the box — no extra configuration needed. Typically you’ll see the data in under 1 s from the time it becomes available via RPC, though larger delays are possible in some cases.

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How do I enable GraphQL subscriptions for local runs?

Add the --subscription flag to the serve command in your commands.json:
See Subscriptions for detailed configuration options.

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Is there a healthcheck endpoint for the indexer?

Yes! The processor exposes Prometheus metrics at the /metrics endpoint (port from PROCESSOR_PROMETHEUS_PORT, falling back to PROMETHEUS_PORT).
For squids deployed to SQD Cloud, metrics are publicly exposed. See Monitoring in the Cloud for details.

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Do squids have a debug mode?

Yes. Enable debug mode by setting the SQD_DEBUG environment variable:
Use specific namespaces to focus on particular components and reduce log noise during debugging.