Why does Telerik ORM increase the value of an SQL Server database column by 10?

Question

I'm working on an SQL Server database where one of my tables has a column whose value seem to be increased by 10 at a time.

The column (called Customer.Object_id) is a primary key (as can be seen in Microsoft SQL Server Management Studio), but I don't believe that the increase by 10 is handled by SQL Server because, when I use the "Edit" functionality for creating a new tuple, I get the request to fill in that particular column, so it should be handled by something else.

Here is the definition in SQL Server:

As an ORM, I use Telerik, so I guess that this one should be responsible, but I don't see it. The mapping configuration looks as follows:

private MappingConfiguration<CustomerObj> CreateCustomerObjMapping()
{
    var mapping = new MappingConfiguration<CustomerObj>();
    mapping.FieldNamingRules.CaseMode = Telerik.OpenAccess.Metadata.CaseChangeModes.CamelCase;
    mapping.FieldNamingRules.AddPrefix = "_";
    mapping.MapType(o => new
    {
        o.Id,
        o.Name,
        o.BackgroundColor,
        // o.Code,
        o.ForegroundColor
    }).Inheritance(InheritanceStrategy.Vertical).ToTable(new TableName("Customer.Obj", string.Empty));

    mapping.HasDiscriminatorValue(typeof(CustomerObj).FullName);

    return mapping;
}

In here, I don't see any reference to the increase by 10, but I also have no idea how to interpret this information.

The column Id is a normal column (although this one should be the one, being handled for this - that's a strategic mistake, done by my predecessor which I can't change any more).

Does anybody have an idea where the increase by 10 in the Customer.Object_id column is handled?

Answer 1

It seems like Telerik may have opted to use its HighLow key generation mechanism for your entity.

HighLow - Telerik Data Access always needs to associate its persistent types with a primary key. If such is not supplied, Telerik Data Access uses internal mechanism for creating IDs.

The HighLow generator has a default GrabSize of 10. This is supposedly configurable via either code or config.

I don't currently have access to test it -and since the product is deprecated the doc is pretty much stale- but I suspect if you insert more than 1 objects at once in a single transaction they may actually have consecutive Ids. (then skipping to the next 10 for the following transaction)