SIMD-0223
Removes Accounts Delta Hash
Feature Gate Status
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TL;DR
With the introduction of the **Accounts Lattice Hash** (SIMD-215), the merkle-based **Accounts Delta Hash** is redundant and can be removed.
Summary
With the introduction of the **Accounts Lattice Hash** (SIMD-215), the merkle-based **Accounts Delta Hash** is redundant and can be removed.
Motivation
This SIMD follows on from SIMD-215, and shares its motivation: > The main goal is to scale Solana to billions accounts When a block is done being processed, it is frozen. The bank hash is calculated during the freezing process, and includes calculating the **Accounts Delta Hash**. The **Accounts Delta Hash** is the merkle-based hash of the accounts modified in this block. As established in SIMD-215, merkle-based hashing of accounts hinders scaling. And since SIMD-215 added the **Accounts Lattice Hash**, which is a hash of the total account state, the merkle-based hash of only the accounts modified per block is redundant. Therefore the **Accounts Delta Hash** can be removed from the bank hash entirely.
Impact
Only validators will be impacted, and their performance will improve since the merkle-based hashing of modified accounts per block will no longer be performed.
Backwards Compatibility
Incompatible. This changes the bank hash, thus changing consensus.
Security Considerations
None.