未明确维护 PK 索引.在 EF Core 中，它可以通过 KeyBuilder fluent API 进行配置(注意用 HasKey 代替 HasIndex):

The PK index is not maintained explicitly. In EF Core it can be configured via KeyBuilder fluent API (note the HasKey in place of HasIndex):

    builder.Entity<Tenant>().HasKey(c => c.TenantId).ForSqlServerIsClustered(false);
    builder.Entity<Tenant>().HasIndex(c => c.ClusteredId).HasName("ClusteredId").ForSqlServerIsClustered(true);