Persisting state

Apibara indexers are stateless by default, when it's restarted it will start from the starting block again.

State includes:

• Cursor: the latest indexed block number and hash. Used on reconnect.
• Filter: if the indexer is using factory mode, this is the filter used for the main data stream.

When you enable persistence, you will need the following CLI option to name the indexer.

• --indexer-id: the unique id for the indexer. Alternatively, set the INDEXER_ID environment variable.

Persist state to a JSON file on the file system. This option is mostly useful for development and should not be used in production.

• --persist-to-fs: path to a folder where the state will be persisted. Alternatively, use the PERSIST_TO_FS environment variable.

Persist state to a Redis server. This is currently the recommended option for production usage.

• --persist-to-redis: Redis connection string. State will be persisted under the apibara:indexers:<sink-id> key. Alternatively, use the PERSIST_TO_REDIS environment variable.

Persist state to an Etcd cluster.

• --persist-to-etcd: Etcd connection string. Alternatively, use the PERSIST_TO_ETCD environment variable.

We are looking for contributors to add persistence to PostgreSQL and MongoDB. If you are interested in contributing this features, feel free to comment in the MongoDB persistence or PostgreSQL persistence issues.