Event Streaming - Backfill and Recovery

Event Streaming is forward-only. Once a message falls outside its retention window, covered in Event Coverage, it isn't redelivered. To recover that data, reconstruct it from Blockdaemon's other data APIs instead.

Three Backfill Routes

Route	Best for	Backing store
RPC API	Point queries against a specific block or transaction	Archive or full-history nodes, depending on chain. See RPC API Overview for per-chain depth.
REST API	Bulk historical queries (blocks, transactions, balances)	Blockdaemon's own indexers, independent of node history limits. See Historical Data for per-chain depth.
Universal API	One consistent request shape across every supported protocol	A shared database for indexed protocols, direct node access for non-indexed ones.

All three authenticate the same way as the rest of the API: an Authorization: Bearer <API_KEY> header (recommended), an X-API-Key header, or an apiKey query parameter.

Schema Alignment

Data pulled from any of the three routes above comes back in that source's native shape, not the UNIFIED_V1 envelope Event Streaming uses. Reconciling a backfilled range against events already received live requires mapping the fields manually. The mapping differs by chain family.

EVM chains (Ethereum and others in the same family)

Native field	Unified envelope field	Notes
`blockNumber`	`block_number`
`blockHash`	`block_hash`
`hash` (transaction)	`tx_id`
`from`	`transfers[].from`
`to`	`transfers[].to`
`value`	`transfers[].value`	Hex converted to decimal
`status`	`status`	`0x1` maps to `"success"`, `0x0` maps to `"failed"`
`gasUsed`	`fee.gas_used`
`gas`	`fee.gas_limit`
`gasPrice`	`fee.gas_price`
`maxFeePerGas`	`fee.max_fee_per_gas`
`maxPriorityFeePerGas`	`fee.max_priority_fee_per_gas`

UTXO chains (Bitcoin and others in the same family)

Native field	Unified envelope field	Notes
`height`	`block_number`
`hash` (block)	`block_hash`
`time`	`block_timestamp`
`previousblockhash`	`parent_hash`
`txid`	`tx_id`
`hash` (transaction)	`tx_hash`
`vin[]`	`transfers[]` entry	Address in `from`, `event_name` set to `"vin"`
`vout[]`	`transfers[]` entry	Address also in `from` (not `to`), `event_name` set to `"vout"`
`fee`	`fee.value`

Polkadot

Native field	Unified envelope field	Notes
`block_id`	`block_hash`
`date`	`timestamp`
`id` (transaction)	`tx_id`
`meta.extrinsicHash`	`tx_hash`
`events[].source`	`transfers[].from`
`events[].destination`	`transfers[].to`
`events[].amount`	`transfers[].value`
`events[].meta.currency.type`	`transfers[].asset`	Not the top-level `denomination` field
`status`	`status`	Passes through unchanged (for example `"completed"`), not remapped to `"success"`/`"failed"`

Solana

Native field	Unified envelope field	Notes
`slot`	`block_number`	Also duplicated as `blockHeight` in block events
`blockhash`	`block_hash`
`previousBlockhash`	`parent_hash`
`blockTime`	`block_timestamp`

Stellar

Native field	Unified envelope field	Notes
`sequence`	`block_number`	Ledger sequence number
`headerJson.header.previous_ledger_hash`	`parent_hash`
`ledgerCloseTime`	`block_timestamp`
`ledger` (transaction)	`block_number`	On `confirmed_tx` events
`txHash`	`tx_id` and `tx_hash`	Same value maps to both fields
`status`	`status`
`createdAt`	`timestamp`
`account_id` (balance entry)	`address`	On `confirmed_balance` events
`balance` (balance entry)	`value`

block_hash is not populated on confirmed_tx or confirmed_balance events, only on block events. Transfer details for confirmed_tx are decoded from the transaction's operations (source, destination, and payment amount), rather than a single flat field, the exact operation-body path depends on the operation type (payment, path payment, account merge, and so on).