Non-movable components, that when inserted goes into the sparse set storage. The sparse component itself does not need to be moved to the destination archetype during insertion.
Benefits
Doesn't need to move the sparse component itself so slightly faster removals and insertions
Fast iteration of single sparse components since it should just iterate over the densely packed pool/column
Drawbacks
Explicit storage specification
Queries of sparse components are always slower than archetype queries except for two scenarios:
if the query is just interested in a single sparse component (just iterate the dense array of the sparse set)
if fragmentation is very high (like 1-2 entities per archetype, and lots of archetypes)
Non-movable components, that when inserted goes into the sparse set storage. The sparse component itself does not need to be moved to the destination archetype during insertion.
Benefits
Drawbacks