To understand how SQL Server defragments an index, consider a simplified example of pages after many insertions, updates, and deletes, as shown in the following figure.
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What is fragmentation?
What is fragmentation? How to detect fragmentation and how to eliminate it?
A fragmented table is a table where some of its data pages point to pages that are not immediately following pages in the extent, and if all its pages are contiguous in both the allocation plan and the extents, then the table is not fragmented.
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