Index Schema

The index is stored at a single RocksDB database using the following schema:

Block headers

Code	Header
`b'B'`	`serialized header`

Transaction output index

Allows efficiently finding transaction funding a specific output:

Code	Output Hash		Funding TxID	Funding Output Index	Funding value
`b'H'`	`outpointhash` (32 bytes)		`txid` (32 bytes)	`varint`	`varint`

Output to token index

Allows for efficiently checking if output modifies token (create, spends, mints, etc).

Code	Output Hash	Token ID		Amount
`b'K'`	`outpointhash` (32 bytes)	`tokenid` (32+ bytes)		`varint` (consensus serialized)

In Nexa, subgroup tokenID's have the same prefix as their parent and are longer. The parent is 32 bytes, while subgroup's are variable in length.

Amount is serialized in the same way as it is in a script_pubkey.

Token to output index

Allows to lookup tokin origin and full token history.

Code	Token ID	Subtoken ID / commitment	Funding output hash
`b'A'`	`tokenid` (32 bytes)	`data` (variable length)	`outpointhash`

For tokens that are not subtokens (nexa) / do not have commitment (bch), data is an empty vector.

For nexa, the fields tokenid + data concatinated make the full token ID.

ScriptSig to output index

Allows efficiently finding all funding transactions for a specific address:

Code	Script Hash Prefix	Flags		Funding output hash
`b'O'`	`SHA256(script)`	1 byte		`outpointhash`

Flags: - 0x00: Generic output - 0x01: Output has token

Transaction input index

Allows efficiently finding spending transaction of a specific output:

Code	Output Hash		Spending TxID	Input index
`b'I'`	`output hash` (32 bytes)		`txid` (32 bytes)	`u32`

TxID to confirmation height index

In order to save storage space, we store the full transaction IDs once, and use their 8-byte prefixes for the indexes above.

Code	Transaction ID		Confirmed height
`b'T'`	`txid` (32 bytes)		`varint`

Note that this mapping allows us to use getrawtransaction RPC to retrieve actual transaction data from without -txindex enabled (by explicitly specifying the blockhash).

CashAccount index

Allows finding all transactions containing CashAccount registration by name and block height.

Code	Account name	Registration TxID Prefix
`b'C'`	`SHA256(name#height)`	`txid`

Other prefixes in use

b'L' - Latest header tip
b'VER - Database version marker