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Editorial Team
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Asked: 2026-05-24T00:07:41+00:00

The Definitive Guide to Scaling out SQL Server 2005 : if you create a

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The Definitive Guide to Scaling out SQL Server 2005:

if you create a nonclustered index and don’t already have a clustered
index, SQL Server creates a “phantom” clustered index because
nonclustered indexes always point to clustered index keys.

  1. What rules does SQL Server use to determine which column/columns will the phantom clustered index be created on?

  2. If it is on the primary key of that table (quick guess), what rules does SQL Server use to determine which column/columns will the phantom clustered index be created on for a table without primary keys?

(question targeted at any version of SQL Server 2005 and beyond)

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1 Answer

  1. Editorial Team

    When you define a primary key, SSMS will by default make that the clustered index. But if you specifically create a table without a clustered index, you are creating a heap table. SQL Server uses an internal value for referencing rows, but it is not any of your columns. The following may help:

    On a Heap Table, what does a non-clustered index use as a pointer to a row?

    http://msdn.microsoft.com/en-us/library/aa964133%28v=sql.90%29.aspx

    http://www.mssqltips.com/tip.asp?tip=1254

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