For more information, see Disable Indexes and Constraints and Enable Indexes and Constraints.
REORGANIZE a rowstore index For rowstore indexes, REORGANIZE specifies to reorganize the index leaf level.
OFF or is not specified The intermediate-level pages are filled to near capacity.
This leaves sufficient space for at least one row of the maximum size that the index can have, based on the set of keys on the intermediate pages.
Doing so may cause degraded performance or excessive memory consumption during these operations.