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SQL Server heap (no clustered index)

Part of the Schema & indexes check · fix arrives as a guide

What it is

A SQL Server table is a heap — it has no clustered index.

Why it matters

Rows are stored unordered, so range scans read more pages than necessary and forwarded records accumulate as rows are updated and grow. Performance degrades with write volume rather than staying flat.

How to fix it

Add a clustered index, typically on the primary key or on the column the table is most often ranged over. Narrow, ever-increasing keys work best since the clustering key is carried in every non-clustered index.

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