Function frame_support::storage::migration::clear_storage_prefix

pub fn clear_storage_prefix(
    module: &[u8],
    item: &[u8],
    hash: &[u8],
    maybe_limit: Option<u32>,
    maybe_cursor: Option<&[u8]>,
) -> MultiRemovalResults

Attempt to remove all values under a storage prefix by the module, the map’s item name and the key hash.

All values in the client overlay will be deleted, if maybe_limit is Some then up to that number of values are deleted from the client backend by seeking and reading that number of storage values plus one. If maybe_limit is None then all values in the client backend are deleted. This is potentially unsafe since it’s an unbounded operation.

Cursors

The maybe_cursor parameter should be None for the first call to initial removal. If the resultant maybe_cursor is Some, then another call is required to complete the removal operation. This value must be passed in as the subsequent call’s maybe_cursor parameter. If the resultant maybe_cursor is None, then the operation is complete and no items remain in storage provided that no items were added between the first calls and the final call.