Migrate non-stable storage to stable storage on single canister

Developers
,
1

Im busy migrating non-stable storage data to stable storage on the same caninster. I already wiped my first canister by accident so I was wondering;

  • can non-stable and stable storage co-exist on a canister?
  • if not, how would i migrate the data the easiest way?
  • if so would non-stable memory where the data is restored by pre- post-upgrade conflict with stable memory?
pub static NON_STABLE_DATA: RefCell<Data> = RefCell::new(Data::default());
pub static STABLE_DATA: RefCell<StableCell<Data, Memory>> = RefCell::new(
            StableCell::init(
                MEMORY_MANAGER.with(|m| m.borrow().get(MemoryId::new(0))),
                Data::default(),
            ).expect("failed")
        );

for the migration i had somehting like this

#[update]
pub fn migrate_to_stable() {
    let data = NON_STABLE_DATA.with(|d| d.borrow().clone());
    let _ = STABLE_DATA.with(|stable| {
        stable.borrow_mut().set(data)
    });
}
2

I’m by no means an expert here, my numerous stupid questions on the forum as proof :sweat_smile:. However, yes I can confirm that heap and stable memory can coexist.

An example illustrating this can be found in the stable structures library repository: https://github.com/dfinity/stable-structures/tree/main/examples/src/quick_start

3

Yes, we’ve written that example specifically for that purpose. The canisters holding the Bitcoin state, for instance, use the exact approach that’s in the quickstart example pointed to above.

4

Thanks thats a relief, going to give it an other try