schema.md

Index Schema

The index is stored as three RocksDB databases:

• txstore
• history
• cache

Indexing process

The indexing is done in the two phase, where each can be done concurrently within itself. The first phase populates the txstore database, the second phase populates the history database.

NOTE: in order to construct the history rows for spending inputs in phase #2, we rely on having the transactions being processed at phase #1, so they can be looked up efficiently (using parallel point lookups).

After the indexing is completed, both funding and spending are indexed as independent rows under H{scripthash}, so that they can be queried in-order in one go.

txstore

Each block results in the following new rows:

• "B{blockhash}" → "{header}"

• "X{blockhash}" → "{txids}" (list of txids included in the block)

• "M{blockhash}" → "{metadata}" (block weight, size and number of txs)

• "D{blockhash}" → "" (signifies the block is done processing)

Each transaction results in the following new rows:

• "T{txid}" → "{serialized-transaction}"

• "C{txid}{confirmed-blockhash}" → "" (a list of blockhashes where txid was seen to be confirmed)

Each output results in the following new row:

• "O{txid}{vout}" → "{scriptpubkey}{value}"

When the indexer is synced up to the tip of the chain, the hash of the tip is saved as following:

• "t" → "{blockhash}"

history

Each funding output (except for provably unspendable ones) results in the following new row (H is for history, F is for funding):

• "H{funding-scripthash}{funding-height}F{funding-txid:vout}{value}" → ""

Each spending input (except the coinbase) results in the following new rows (S is for spending):

• "H{funding-scripthash}{spending-height}S{spending-txid:vin}{funding-txid:vout}{value}" → ""

• "S{funding-txid:vout}{spending-txid:vin}" → ""

Liquid/elements chains also have the following indexes for issued assets:

• "i{asset-id}" → "{issuing-txid:vin}{prev-txid:vout}{issuance}{reissuance_token}"
• "I{asset-id}{issuance-height}I{issuing-txid:vin}{is_reissuance}{amount}{tokens}" → ""
• "I{asset-id}{funding-height}F{funding-txid:vout}{value}" → ""
• "I{asset-id}{spending-height}S{spending-txid:vin}{funding-txid:vout}{value}" → ""

cache

Holds a cache for aggregated stats and unspent TXOs of scripthashes.

The cache is created on-demand, the first time the scripthash is requested by a user.

The cached data is kept next to the blockhash the cache is up-to-date for. When requesting data, the cache is updated with the new history rows added since the blockhash. If the blockhash was since orphaned, the cache is removed and re-computed.

• "A{scripthash}" → "{stats}{blockhash}" (where stats is composed of tx_count, funded_txo_{count,sum} and spent_txo_{count,sum})

• "U{scripthash}" → "{utxo}{blockhash}" (where utxo is a set of (txid,vout) outpoints)

Elements only:

• "z{asset-id}" → "{stats}{blockhash}" (where stats is composed of tx_count, issuance_count, issued_amount, burned_amount, has_blinded_issuances, reissuance_tokens, burned_reissuance_tokens)