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SDK FAQ

Common questions and answers 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 Dashboards - Track addresses and internal transactions across multiple protocols
  • NFT Marketplaces - Index dynamic sets of NFT contracts and trading activity
  • 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 <1sec 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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How does Squid SDK handle unfinalized blocks?

The SQD Network serves finalized blocks and is typically ~1000 blocks behind the tip. Recent and unfinalized blocks are seamlessly handled by the SDK from a complementary RPC data source configured in your processor.
Potential chain reorganizations are automatically handled under the hood, ensuring data consistency.
For detailed information, see Indexing unfinalized blocks.

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What is the latency for the data served by the squid?

Since the ArrowSquid release, Squid SDK can ingest unfinalized blocks directly from an RPC endpoint, making indexing real-time with minimal latency.
Configure your RPC endpoint in the processor to enable real-time indexing of the latest blocks.

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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:
commands.json
{
  "commands": {
    "serve:dev": {
      "cmd": ["npx", "squid-graphql-server", "--subscription"]
    }
  }
}
See Subscriptions for detailed configuration options.

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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: 
SELECT * FROM squid_processor.status;
Reset processor status: 
DROP SCHEMA squid_processor CASCADE;
File-based datasets: Squids using file-based storage store their status in status.txt by default. This can be customized using database hooks.

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Is there a healthcheck endpoint for the indexer?

Yes! The processor exposes Prometheus metrics at the ${process.env.PROMETHEUS_PORT}/metric endpoint.
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:
.env
# Enable all debug messages
SQD_DEBUG=*

# Enable specific namespace (e.g., SQD Network queries)
SQD_DEBUG=sqd:processor:archive
Use specific namespaces to focus on particular components and reduce log noise during debugging.