Initializing the Merkle Tree
The first step in utilizing a Merkle tree is to initialize it. A Merkle tree has three fundamental parameters: 1) Depth (capacity), 2) Buffer size (concurrency / latency), and 3) Canopy height (composability).
Depth
The capacity of a perfectly balanced concurrent Merkle tree is 2^{DEPTH}. This means that trees can be configured to hold anywhere from eight leaves to a billion (2^30). In this case, leaves can be NFTs.
Buffer Size
Buffer size is an approximation of the number of concurrent updates that can happen in the same block. Merkle trees typically have an issue whereby any modification of the tree causes any previously computed proofs to go out-of-date, but with this novel concurrent Merkle tree implementation, stale proofs can be fast-forwarded and still be accepted by the smart contract. A buffer size of 64 means that any given proof will still remain valid for up to 64 updates of the tree, after which it must be recomputed. Buffer size can range from eight to 2048.
Canopy Height
Canopy height specifies the portion of the tree that remains on-chain, reducing the amount of proofs that have to be submitted by clients for verification. Given the current transaction size limits on Solana, this is the only feasible way to pass enough proofs to be able to validate the existence of trees with a depth > 20. Canopy height maxes out at 17.
Initialization Strategies
Rather than initializing one giant tree to hold everything, I recommend issuing numerous, smaller trees of varying sizes. This reduces write-lock contention on the tree account, as well as provides more opportunities for composability by reducing the number of proofs needed to be submitted for any given modification.
Choosing the Right Canopy Height
Choose a canopy height that maximizes composability – while it costs more in rent, a canopy height that is DEPTH-3 provides a similar interface to existing NFT-related smart contracts that already pass 3 accounts. For example, a tree of depth 20 could have a canopy of 17 so that clients only need to submit three proofs to make any modification to a tree.
Conclusion
By following the guidelines outlined in this article, you can successfully initialize and utilize a Merkle tree. With a thorough understanding of depth, buffer size, and canopy height, you can tailor your Merkle tree to meet your specific needs and achieve maximum composability and scalability.
FAQs
- Q: What is the purpose of a Merkle tree?
A: A Merkle tree is a data structure that enables efficient and secure data storage and verification. It allows for fast proof-of-possession and validation of digital assets, making it an ideal solution for applications requiring secure and scalable storage of data.
- Q: What is the optimal buffer size for a Merkle tree?
A: The optimal buffer size depends on the specific use case and requirements of your application. However, a buffer size of 64 is generally recommended, as it provides a good balance between concurrency and latency.
- Q: Why is canopy height important?
A: Canopy height determines the portion of the tree that remains on-chain, affecting the amount of proofs that need to be submitted for verification. A well-chosen canopy height can significantly impact the scalability and composability of your Merkle tree.
- Q: Can I initialize a single giant tree instead of multiple smaller trees?
A: While possible, initializing a single giant tree can lead to increased write-lock contention and reduced composability. It is generally recommended to use multiple smaller trees for improved scalability and composability.
