INF: FILLFACTOR Settings in SQL Server

ID Number: Q75669

1.10

OS/2

Summary:

When FILLFACTOR is set to 100, the internal and leaf pages of the

index are completely filled. In contrast, when FILLFACTOR is set to 0

(zero), only the leaf pages are completely filled, and space is left

in non-leaf pages for at least one more entry (two for non-unique

clustered indexes).

FILLFACTOR 100 should be used only when there will be no inserts or

updates that cause page splits, because the page split algorithm assumes

that there will be at least enough space for one more entry in an

internal page.

If FILLFACTOR is set to any value other than 0 or 100, space is left

in the non-leaf pages for one entry (two for non-unique clustered

indexes), and the space left in the leaf pages is such that no leaf

page is filled beyond the percentage specified by FILLFACTOR:

FILLFACTOR Internal Page Leaf Page

---------- ------------- ---------

0 percent 1 free slot* 100 percent full

1-99 percent 1 free slot* <= FILLFACTOR percent full

100 percent 100 percent full 100 percent full

* Two free slots for non-unique clustered indexes.

Additional reference words: 1.10