[Matrix]: write materialized portions when they are materialized.
[Matrix]: write materialized portions when they are materialized.

icoming/FlashX,icoming/FlashGraph,icoming/FlashX,icoming/FlashGraph,icoming/FlashX,icoming/FlashGraph,icoming/FlashGraph,flashxio/FlashX,icoming/FlashX,flashxio/FlashX,flashxio/FlashX,icoming/FlashX,flashxio/FlashX,icoming/FlashGraph,flashxio/FlashX,flashxio/FlashX