Answer
Fragmentation scatters index pages, causing more I/O during seeks and reducing read-ahead efficiency. High fragmentation slows down queries and increases disk activity. Regular index maintenance helps restore performance.
Quick Answer
Index fragmentation means leaf pages are out of logical order. When SQL Server does a range scan, it should read pages sequentially — fragmentation turns that into random I/O. Over 30% fragmentation is worth addressing. Reorganize (online, light) for moderate fragmentation; Rebuild (offline or online with Enterprise) for heavy fragmentation.
S
SugharaIQ Editorial Team
Verified Answer
This answer has been peer-reviewed by industry experts holding senior engineering roles to ensure technical accuracy and relevance for modern interview standards.
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Source: SugharaIQ