Spread Storage Layout

Storage Organization

The following schema depicts the storage which is exposed to ink! by the contracts pallet:

ink!'s storage operates by storing and loading entries into and from a single storage cell. At the moment there is no way to customize this behavior. Depending on the data we're dealing with, this can end up being good or bad.

For example, if we have a somewhat small ink_prelude::vec::Vec loading all the elements at the same time can be advantageous - especially if we expect our message to interact with most of them in a single call.

On the other hand, this can be problematic if we're loading a large Vec and only operating on a few elements.

Spreading

ink! spreads information to as many cells as possible. For example if you have the following #[ink(storage)] struct every field will live in its own single storage cell. Note that for b all 32 bytes will share the same cell!

#[ink(storage)]
pub struct Spread {
    a: i32,
    b: [u8; 32],
}

The following schema depicts the storage layout for a vector with three elements, persisted to storage in a spread layout.