How can you create Clustered Indexes with Fluent NHibernate?

Question

I am using Fluent-NHibernate (with automapping) to generate my tables but would like to choose a different clustered index than the ID field which is used by default. How ca

Answer 1

This is an old post, but I hope could help someone else. This come from my experience on MS SQL Server. I believe different platforms require different solutions, but this should be a good starting point.

NHibernate doesn't set the CLUSTERED index on the primary key. It's the SQL Server default behavior. As there can be only one CLUSTERED per table, we need first to avoid the CLUSTERED creation on the primary key.

The only way I found to accomplish this is to create a custom Dialect, overriding the propery PrimaryKeyString. NHibernate's default comes from Dialect.cs:

    public virtual string PrimaryKeyString
    {
        get { return "primary key"; }
    }

For SQL Server

    public override string PrimaryKeyString
    {
        get { return "primary key nonclustered"; }
    }

This will force SQL Server to create a NONCLUSTERED primary key. Now you can add your own CLUSTERED index on your favorite column through the tag in the XML mapping file.

  
    create clustered index IX_CustomClusteredIndexName on TableName (ColumnName ASC)
  
  
    drop index IX_CustomClusteredIndexName ON TableName