Wildcard Search allows retrieving multiple key-value pairs stored under a common hierarchical structure. In this case, keys are organized such that a context_entity_id can contain multiple context_ids, and each context_id can have multiple memory_ids. This method enables fetching all associated data efficiently.
So, basic idea is that you if you want to fetch all context_id keep it none in memory_context object and if you want to fetch all memory_id keep it none in memory_context.