stable-memory

Stable memory persists canister state across upgrades by using StableBTreeMap, StableCell, and MemoryManager to store data outside the heap, preventing data loss when canisters are redeployed on the Internet Computer.

Canisters lose data on upgrade because heap memory is reset during redeployment. You need stable memory structures like StableBTreeMap to preserve user data, counters, and configuration across upgrades without requiring manual migration.

Stable memory integration supports both Motoko and Rust canisters, providing upgrade hooks and safe serialization patterns to ensure durable storage across upgrades in either language environment.

Initialize a stable memory structure like StableBTreeMap, add your data, then upgrade the canister to verify that the data persists successfully across the redeployment without loss.

The best way to safely migrate canister data during an upgrade is to use stable memory structures with proper upgrade hooks and safe serialization patterns, ensuring persistent storage via MemoryManager and StableBTreeMap.

You need MemoryManager when your canister requires durable storage across upgrades and uses multiple stable memory structures, as it manages memory allocation for StableBTreeMap and StableCell to safely persist state.