Coinstats Index

The coinstats index, enabled with -coinstatsindex=1, is an optional Bitcoin Core database that precomputes statistics about the unspent transaction output (UTXO) set at every block height. Its purpose is to make the gettxoutsetinfo RPC fast and queryable for arbitrary past heights. Without the index, computing things like the total number of UTXOs, the total coin supply, or the value of unspendable outputs requires iterating the entire UTXO set, which can take minutes and only answers for the current tip.

What it tracks

Stored at indexes/coinstatsindex/, the index maintains a running, height-by-height accounting of the UTXO set: the count of unspent outputs, the total amount of bitcoin in circulation, the sum of block-reward subsidies and fees, and the value of provably unspendable outputs such as OP_RETURN burns. Because it keeps this state per block, an operator can ask for the supply or UTXO count as of any historical height instantly, which is invaluable for auditing the 21-million issuance schedule against the live chain.

Who uses it

Researchers, monetary auditors, and anyone independently verifying Bitcoin's supply curve rely on the coinstats index, as do dashboards that chart UTXO-set growth over time. Like other optional indexes it adds disk and an initial backfill pass, and it can be built alongside a normal or even a pruned node since it summarizes UTXO state rather than pointing into old block files.

For related indexes, see the transaction index (txindex) and the block filter index.