Sql-server – Change clustered index without dropping the primary key

clustered-indexforeign keyfull-text-searchprimary-keysql server

In the past, I have chosen the datetime column created as inappropriate clustered index in the table.

Now I concluded (base on the execution plan) that it would be better to choose the ID identity primary key as the clustered key, because it is referenced as foreign key very often.

I would like to drop the current clustered key and create a new, but I cannot drop the primary key, because that the full-text index is dependent on that primary key.

Can I just switch primary key to clustered index or do I need to drop the primary key and the chain of all dependent objects?

Bellow you will find table definition and clustered index definition.

CREATE TABLE [dbo].[Realty](
    [Id] [int] IDENTITY(1,1) NOT NULL,  
    [Created] [datetime] NOT NULL,
    ....

 CONSTRAINT [PK_Realty] PRIMARY KEY NONCLUSTERED 
(
    [Id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON, FILLFACTOR = 90) ON [PRIMARY]
...


CREATE CLUSTERED INDEX [Created] ON [dbo].[Realty]
(
    [Created] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON, FILLFACTOR = 90) ON [PRIMARY]
GO

Best Answer

Just drop the existing clustered index, then create a new one on the ID column.

DROP INDEX [Created] ON dbo.Realty;
GO

CREATE UNIQUE CLUSTERED INDEX CX_Realty ON dbo.Realty (ID);
GO

Of course, you'll want to do this during a maintenance window so you don't cause too much blocking. If you have Enterprise Edition you can do the CREATE INDEX operation online by adding WITH (ONLINE=ON) to the statement.

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