Chapter 6 – Utreexo


Chapter 6 of Bitcoin: A Work In Progress explains Utreexo, a more compact format to store the ever growing UTXO set (list of coins in existence). If you enjoyed this chapter, buy the book or the e-book.



Whenever a new Bitcoin transaction is made, Bitcoin nodes use a UTXO set to determine that the coins being spent really exist (see chapter 5). This UTXO set is currently several gigabytes in size and continues to grow over time, and there’s no upper limit to how big it can potentially get.

Because Bitcoin nodes perform best if the UTXO set is kept in RAM, and because RAM is a relatively scarce resource for computers, it would benefit a node’s performance if the UTXO set could be stored in a more compact format. This is the promise of Utreexo.

If you enjoyed this chapter, buy the book or the e-book.