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Version: Current

FAQ

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

Here is an incomplete list:

  • DeFi dashboards, tracking addresses and internal transactions
  • NFT marketplaces, with a dynamic sets of NFT contracts to watch
  • Historical price feeds, tracking Uniswap trades and Chainlink oracle contracts
  • Mining smart contract deployments and the bytecode
  • Real-time bots (<1sec delay) triggered by on-chain activity

How does Squid SDK handle unfinalized blocks?​

The Subsquid Network only serves finalized blocks and is typically ~1000 blocks behind the tip. The most recent blocks, as well as the unfinalized blocks are seamlessly handled by the SDK from a complementary RPC data source, set by the chain config. Potential chain reorgs are automatically handled under the hood. See Indexing unfinalized blocks for details.

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

Since the ArrowSquid release, the Squid SDK has the option to ingest unfinalized blocks directly from an RPC endpoint, making the indexing real-time.

How do I enable GraphQL subscriptions for local runs?​

Add --subscription flag to the serve command defined in commands.json. See Subscriptions for details.

How do squids keep track of their sync progress?​

Depends on the data sink used. Squid processors that use TypeormDatabase keep their state in a schema, not in a table. By default the schema is called squid_processor (name must be overridden in multiprocessor squids). You can view it with

select * from squid_processor.status;

and manually drop it with

drop schema squid_processor cascade;

to reset the processor status.

Squids that store their data in file-based datasets store their status in status.txt by default. This can be overridden by defining custom database hooks.

Is there a healthcheck endpoint for the indexer?​

Yes, the processor exposes the key prometheus metrics at the ${process.env.PROMETHEUS_PORT}/metric endpoint. The squids deployed to the Subsquid Cloud also publicly explose the metrics, see Monitoring in the Cloud