What is fill factor and pad index? A fill factor is a specification done during the creation of indexes so that a particular amount of space can be left on a leaf level page to decrease the occurrence of page splits when the data has to be accommodated in the future.
A pad index specifies index padding. When it is set to ON, then the free space percentage per the fill factor specification is applied to the intermediate-level pages of the index. When it is set to OFF, the fill factor is not specified and enough space is left for a maximum size row that an index can have