Embeddable & extensible chain-indexer for Cardano
Hydrant is an embeddable, extensible and fast chain-indexer for Cardano, designed to distill the chain to only the data needed for your usecase.
- High-level API for defining your own indexer
- Rkyv + LMDB for zero-copy memory-mapped storage
- Atomic block writes
- Node-to-Node (N2N) protocol, no Cardano Node required
- Fast syncing (~30 minutes with localhost node)
Hydrant handles finding the intersection of its DB to Cardano Node and periodically requests roll forward and roll backward events from the chain-sync protocol (with block fetch batching). The blocks are decoded and stored in a volatile block DB via LMDB. The consumer defines a struct implementing the Indexer trait, which receives a handle to the write transaction, to enable atomic writes across both the volatile DB and consumer's DB.
pub trait Indexer {
fn insert_tx(&self, wtxn: &mut heed::RwTxn, tx: &Tx) -> Result<bool>;
fn delete_tx(&self, wtxn: &mut heed::RwTxn, tx: &Tx) -> Result<()>;
fn insert_datum(&self, wtxn: &mut heed::RwTxn, datum_hash: &DatumHash, datum: &Datum) -> Result<bool>;
fn delete_datum(&self, wtxn: &mut heed::RwTxn, datum_hash: &DatumHash) -> Result<()>;
fn clear(&self, wtxn: &mut heed::RwTxn) -> Result<()>;
}Returning true from insert_tx/insert_datum tells the volatile DB to track the tx/datum, sending a delete_* event when rolled back.
This project uses the Node-to-Node (N2N) protocol for chainsync and blockfetch, such that you don't need a local node, just a relay. But for the purposes of development, we use a local node to speed-up sync times. If nix develop takes a long time to build, ensure that you have accepted the flake config such that the IOG cache will be used for downloading cardano-node.
Currently, the cardano-node runs against mainnet (please feel free to PR supporting preview) which uses ~250GBs of disk space and ~12GB of RAM.
nix develop --accept-flake-config
start-node # downloads configuration and starts the node
# in another shell
nix develop --accept-flake-config
cargo run